DITHIENOPYRROLE GROUPS

The present invention relates to a benzoheterodiazole compound disubstituted with dithienopyrrole groups.

More particularly, the present invention relates to a benzoheterodiazole compound disubstituted with dithienopyrrole groups having the specific general formula (I) reported below.

Said benzoheterodiazole compound disubstituted with dithienopyrrole groups having general formula (I) can be advantageously used as an electron acceptor compound in organic photovoltaic devices (or solar devices) selected, for example, from binary, ternary, quaternary organic photovoltaic cells (or solar cells), having simple or tandem architecture, organic photovoltaic modules (or solar modules), both on a rigid support and on a flexible support. Furthermore, said benzoheterodiazole compound disubstituted with dithienopyrrole groups having general formula (I) can be advantageously used in perovskite-based photovoltaic cells (or solar cells) in the layer based on electron transport material (Electron Transport Layer - ETL). Furthermore, said benzoheterodiazole compound disubstituted with dithienopyrrole groups having general formula (I) can be advantageously used in the construction of organic thin film transistors (OTFTs), or organic field effect transistors (OFETs).

The present invention also relates to an organic photovoltaic device (or solar device) selected, for example, from binary, ternary, quaternary organic solar cells, having simple or tandem architecture, organic photovoltaic modules (or solar modules), both on a rigid support and on a flexible support, comprising at least one benzoheterodiazole compound disubstituted with dithienopyrrole groups having general formula (I).

The present invention also relates to a perovskite -based photovoltaic cell (or solar cell) in which the layer based on electron transport material (Electron Transport Layer - ETL) comprises at least one benzoheterodiazole compound disubstituted with dithienopyrrole groups having general formula (I).

The present invention also relates to organic thin film transistors (OTFTs), or organic field effect transistors (OFETs) comprising at least one benzoheterodiazole compound disubstituted with dithienopyrrole groups having general formula (I).

The photovoltaic cell (or solar cell) market is currently dominated by crystalline silicon-based cells, due to their high efficiency and thanks to a well- established technology. Photovoltaic cells (or solar cells) can be divided into generations based on the characteristics of the photoactive material used in them. Thus, for example, there are: first generation photovoltaic cells (or solar cells) based on crystalline silicon, commercially available; second generation photovoltaic cells (or solar cells) such as, for example, copper-indium gallium-based photovoltaic cells (or solar cells) (CIGS), or cadmium telluride-based photovoltaic cells (or solar cells) (CdTe), or gallium arsenide -based photovoltaic cells (or solar cells) (GaAs) and amorphous silicon, commercially available; third generation photovoltaic cells (or solar cells) such as, for example, copper zinc tin sulfide-based photovoltaic cells (or solar cells) (CZTS), or perovskite-based photovoltaic cells (or solar cells), or dye sensitized photovoltaic cells (or solar cells) (DSSCs), or quantum dots-based photovoltaic cells (or solar cells), or organic photovoltaic cells (or solar cells) (OPV) based on mixtures comprising electron acceptor compounds (A) which may be small molecules or polymers, and electron donor compounds (D) which may be small molecules or polymers, which are the photovoltaic cells (or solar cells) so-called emerging and subject of continuous studies.

The success of one technology compared to another is influenced by many factors: for example, in the specific case of photovoltaic cells (or solar cells), their success will depend on their efficiency, lightness, cost-effectiveness, stability over time and also on their industrial scalability. In particular, their scalability at an industrial level depends on further factors such as, for example, the abundance and toxicity of the raw materials used, the stability of said raw materials [for example, in some cases, photovoltaic cells (or solar cells) need encapsulation in order to make them stable over time], the simplicity of the technology adopted for their production. An important role is also played by the environmental impact and the life cycle of these photovoltaic cells (or solar cells).

Although organic photovoltaic cells (or solar cells) generally have lower efficiencies with respect to the first and second generation photovoltaic cells (or solar cells) [in recent years, however, there has been an increase in performance comparable to that of photovoltaic cells (or solar) belonging to the other more mature generations that have reached the plateau, and small-scale efficiencies of up to about 18% have been found], they have enormous potential.

For example, among many advantages of organic photovoltaic cells (or solar cells) the following can be mentioned: lightness, flexibility, semi-transparency, activation both in diffused light and by artificial light which makes them usable even in indoor contexts, the ease and potentially low cost of fabrication using normal printing techniques such as, for example, the roll-to-roll (R2R) methodology reported, for example, by Valimaki M. et al., in Nanoscale (2015), Vol. 7, p. 9570-9580. Furthermore, thanks to their flexibility and transparency, organic photovoltaic cells (or solar cells) can be easily integrated into buildings and windows and used in architectural design structures as reported, for example, by Burgues-Ceballos I. et al., in Journal of Material Chemistry A (2020), Vol. 8, p. 9882-9895.

The studies related to organic photovoltaic cells (or solar cells) date back to about 40 years ago as reported, for example, by Tang C. W ., in Applied Physic Letters (1986), Vol. 48, p. 183-185.

The elementary process of converting light into electric current in an organic photovoltaic cell (or solar cell) takes place through the following stages:

1. absorption of photons by the electron donor compound (D) or by the electron acceptor compound (A) [the absorption of each photon leads to the formation of an exciton, i.e. of a pair of charge carriers "electron-electronic gap (or hole);

2. diffusion of the exciton in a region of the compound that has absorbed the photon up to the interface with the compound that has not absorbed the photon [i.e. interface electron donor compound (D)-electron acceptor compound (A)], wherein dissociation of the exciton can occur;

3. dissociation of the exciton in the two charge carriers: electron (-) in the accepting phase [i.e. in the electron acceptor compound (A)] and electron gap (or hole) (+) in the donor phase (i.e. in the electron donor compound);

4. transport of the charges thus formed to the cathode [electron (-) through the electron acceptor compound (A)] and to the anode [electron gap (or hole) (+) through the electron donor compound (D)], with generation of an electric current in the circuit of the organic photovoltaic cell (or solar cell).

The photoabsorption process with exciton formation involves the excitation of an electron from the energy level HOMO (EHOMO) (Highest Occupied Molecular Orbital) to the energy level LUMO (ELUMO) (Lowest Unoccupied Molecular Orbital) of the compound that absorbed the photons. Subsequently, an electron is released from the LUMO energy level (ELUMO) of the electron donor compound (D) to the LUMO energy level (ELUMO) of the electron acceptor compound (A), or an electron is released from the HOMO energy level (EHOMO) of the electron donor compound (D) to the energy level HOMO (EHOMO) of the electron acceptor compound (A).

As mentioned above, in organic photovoltaic cells (or solar cells) the photoactive material is a mixture comprising electron acceptor compounds (A) and electron-donor compounds (D). Both compounds absorb photons generating excitons, and the photogenerated excitons from the electron acceptor compound (A) and from the electron donor compound (D) are separated by electron transfer and electron gap (or hole) transfer. Said electron transfer occurs spontaneously if the energy difference between the energy level LUMO (ELUMO) of the electron donor compound (D) and the energy level LUMO (ELUMO) of the electron acceptor compound (A) (AELUMO, D-A) is greater than zero and in any case greater than a threshold value which depends on the pair electron donor compound (D) - electron acceptor compound (A), and if the energy difference between the energy level HOMO (EHOMO) of the electron donor compound (D) and the energy level HOMO (EHOMO) of the electron acceptor compound (A) (AEHOMO, D-A) is greater than zero and in any case greater than a threshold value which depends on the pair electron donor compound (D) - electron acceptor compound (A). In order to have an efficient dissociation of the exciton in the two charge carriers, the energy levels of the electron donor compound (D) and of the electron acceptor compound (A) must be aligned (i.e. correctly positioned). In order to absorb as much sunlight as possible, it would be best for electron acceptor compounds (A) and electron donor compounds (D) to absorb light of different wavelengths. Generally, a AELUMO. D A > 0.3 eV is required to have an efficient transfer of electrons while, as regards the transfer of electron gaps (or holes), it has been observed that it can be efficient even if AEHOMO, D-A < 0.3 eV [said value must in any case be positive as reported, for example, by Zhan C. et al., in Journal Materials Chemistry A (2018), Vol.6, p. 15433-15455],

Another important characteristic of the compounds used in the production of organic photovoltaic cells (or solar cells) is the mobility of the electrons in the electron acceptor compound (A) and of the electron gaps (or holes) in the electron donor compound (D), which determines the ease with which the electric charges, once photogenerated, reach the electrodes.

The electron mobility, i.e. the mobility of electrons in the electron acceptor compound (A) and of the electron gaps (or holes) in the electron donor compound (D), besides being an intrinsic property of the compounds used, is also strongly influenced by the morphology of the photoactive layer, which in turn depends on the mutual miscibility of the compounds used in said photoactive layer and on their solubility. To this end, the phases of said photoactive layer must not be too dispersed or too segregated.

The morphology of the photoactive layer is also critical as regards the efficiency of the dissociation of the photogenerated electron gap (hole)-electron pairs. In fact, the average lifetime of the exciton is such that it is able to diffuse in the organic material for an average distance, which, for organic compounds, is generally around 10 nm - 20 nm. Consequently, the phases of the electron donor compound (D) and the electron acceptor compound (A) must be organized into nanodomains of comparable size with these diffusion lengths. Furthermore, the contact area (i.e. interface) between the electron donor compound (D) and the electron acceptor compound (A) must be as large as possible and there must be preferential paths to the electrical contacts. Furthermore, this morphology must be reproducible and must not change over time [see, for example, Gaitho F. M. et al., Physical Sciences Reviews (2018), doi: 10.1515/ psr-2017-0102].

Organic photovoltaic cells (or solar cells) are manufactured in the simplest way by introducing a thin layer (about 100 nanometers) of a mixture of the electron acceptor compound (A) and the electron donor compound (D) [bulk heterojunction] between two electrodes, usually made up of indium tin oxide (ITO) (anode) and aluminum (Al) (cathode). Generally, in order to make a layer of this type, a solution of the two components is prepared [i.e. electron acceptor compound (A) and electron donor compound (D)] and, subsequently, a photoactive layer is created on the anode [indium-tin oxide (ITO)] starting from said solution, using suitable deposition techniques such as, for example, spincoating, spray-coating, ink-jet printing, slot die coating, gravure printing, screen printing, and the like. Finally, the counter electrode [i.e. the aluminum (Al) cathode] is deposited on the dried photoactive layer by means of known techniques, for example, by evaporation. Optionally, between the anode and the photoactive layer and/or between the cathode and the photoactive layer, other additional layers can be introduced (called interlayers or buffer layers) capable of performing specific functions of an electrical, optical, or mechanical nature.

Generally, for example, in order to help electron gaps (or holes) reach the anode [indium tin oxide (ITO)] and at the same time to block the transport of electrons, thus improving the collection of positive charges by the anode and inhibiting the recombination phenomena, before creating the photoactive layer starting from the mixture of the electron acceptor compound (A) and the electron donor compound (D) as described above, a layer starting from an aqueous suspension comprising PEDOT:PSS [poly(3,4- ethylenedioxythiophene)polystyrene sulphonate] is deposited, using suitable deposition techniques such as, for example, spin-coating, spray-coating, ink-jet printing, slot die coating, gravure printing, screen printing, and the like.

At the state of the art, the most commonly used electron donor compound (D) in the production of organic photovoltaic cells (or solar cells) is regioregular poly (3 -hexylthiophene) (P3HT). This polymer has excellent electronic and optical characteristics, e.g., good values of HOMO (EHOMO) and LUMO (ELUMO) energy levels, good molar absorption coefficient (E), good solubility in the solvents that are used to manufacture the organic photovoltaic cells (or solar cells), and a moderate mobility of the electronic gaps (or holes).

Other examples of polymers which can be advantageously used as electron donor compounds (D) are: PCDTBT {poly[N-9"-heptadecanyl-2,7-carbazole-alt- 5,5-(4',7'-di-2-thienyl-2',l',3'-benzothiadiazole] }, PCPDTBT {poly[2,6-(4,4-Z>zs- (2-ethylhexyl)-4H-cyclopenta[2,l-b;3,4-b']-dithiophene)-a/t- 4,7-(2,l,3- benzotiadiazole)] }, the polymer PffBT4T-2OD {poly[(5,6-difluoro-2,l,3- benzothiadiazol-4,7-diyl)-a/t-(3,3'"-di(2-octyldodecyl)-2,2' ,5',2'';5'',2'''- quaterthiophene-5,5'"-diyl)] }.

As for electron acceptor compounds (A), the history of organic photovoltaic cells (or solar cells) can be divided into two periods as reported, for example, by Zhan C. et al., in Journal of Material Chemistry A (2018), Vol. 6, p. 15433-15455: the period of fullerene compounds in which the electron acceptor compounds (A) were derivatives of fullerene such as, for example, [6,6]- phenyl-Cei-butyric acid methyl ester (PC61BM), (6,6)-phenyl-C7i-butyric acid methyl ester (PC71BM), still widely used today also in coupling with non-fullerene electron acceptor compounds (A) in ternary or quaternary organic photovoltaic cells (or solar cells); the period of non-fullerene compounds in which the electron acceptor compounds (A) were non-fullerene compounds as reported, for example, by Yan H. et al., in Chemical Reviews (2018), Vol. 118, 7, p. 3447-3507; Yang Y. et al, in Nature Photonics (2018), Vol. 12, 131-142; Gao F. et al., in Nature Materials (2018), Vol. 17, p. 119-128; McCulloch I. et al, in Chemical Society Reviews (2019), Vol. 48, p. 1596-1625, which led to an improvement in the efficiencies of organic photovoltaic cells (or solar cells) up to 18%, approaching the efficiencies of first and second generation photovoltaic cells (or solar cells) and thus increasing the interest in this type of technology.

The fullerene derivatives reported above offer certain advantages related to their structure such as, for example, stability and efficient isotropic transport, due to the delocalization of the energy level LUMO (ELUMO) over their entire surface. However, alongside these advantages, fullerene derivatives suffer from some intrinsic problems such as, for example: weak absorption in the visible and near infrared regions (NIR); low miscibility with most polymers; high tendency to aggregate, which can create long-term morphological stability problems; values of the HOMO (EHOMO) and LUMO (ELUMO) energy levels are not easily modulated, as even the introduction of functional groups does not greatly modify the energy levels of said fullerene derivatives.

Compared to fullerene derivatives, non-fullerene compounds have significant advantages such as, for example: modulable band-gap values since, depending on the type of compound and its design, non-fullerene compounds can absorb light in various areas of the solar spectrum and extend the absorption up to the near infrared (NIR);

(EHOMO) and LUMO (ELUMO) energy levels that can be modulated according to the structure of the compound; adjustable planarity and crystallinity with greater control of the morphology of the active layer and a consequent increase in the stability of the photovoltaic cells (or solar cells) in which they are used.

Non-fullerene electron acceptor compounds are, therefore, known in the art.

For example, Yao J. et al, in Polymer Chemistry (2013), Vol. 4, p. 4631-4638, report non-fullerene electron acceptor compounds comprising perylene diimide capable of yielding organic photovoltaic cells (or solar cells) with efficiencies up to 1.95%.

Liu J. et al., in Nature Energy (2016), Vol. 1, Article No. 16089, p. 1- 7, report non-fullerene electron acceptor compounds comprising naphthalene diimide capable of providing organic photovoltaic cells (or solar cells) with efficiencies up to 9.5%.

Lin Y. et al., in Advanced Materials (2015), Vol. 27, Issue 7, p. 1170- 1174, report the design and synthesis of a new electron acceptor compound called ITIC based on a "core" comprising seven fused rings (indacenodithene[3,2-b]thiophene, IT) substituted with four 4-hexyl- phenyl groups, and end-capped with 2-(3-oxo-2,3-dihydroinden-l- ylidene)malononitrile (INCN) groups capable of giving organic photovoltaic cells (or solar cells) with efficiencies up to at 6.8%.

Sauve G., in The Chemical Record (2019), Vol. 19, p. 1078-1092, reports a series of electron acceptor compounds with different designs including a conjugated compound A-D-A with a planar structure wherein D is a rigid unit and has orthogonal side chains so as to control the aggregation capable of providing organic photovoltaic cells (or solar cells) with efficiencies up to 14%.

Yao H. et al., in Nature Communications (2019), Vol. 10, p. 10351- 10355, report non-fullerene chlorinated electron acceptor compounds capable of giving organic photovoltaic cells (or solar cells) with efficiencies up to 16.5%.

Zou Y. et al., in Joule (2019), Vol. 3, p. 1140-1151, report a new class of non-fullerene electron acceptor compounds, having a central "core" based on fused rings (dithienothiophen[3.2-b]-pyrrolobenzothiadiazole) and benzothiadiazole capable of giving organic photovoltaic cells (or solar cells) with efficiencies up to 15.7%.

The above electron acceptor compounds having a long central "core" based on fused rings, while being able to give organic photovoltaic cells (or solar cells) having excellent performance, particularly in terms of efficiency, are very complicated molecules whose synthesis requires either many steps, or the use of very expensive starting materials and, consequently, their industrial development can be problematic.

Currently, non-fullerene electron acceptor compounds with a shorter central core are emerging.

For example, Chen H. et al, in Journal of Material Chemistry A (2018), Vol. 6, p. 12132-12141, report three non-fullerene electron acceptor compounds of the acceptor-donor-core-donator-acceptor (A-D- C-D-A) type which have the same electron donor part (D) and the same electron acceptor part (A) terminal but a different "core" (C). Among said electron acceptor compounds, the one having a 2,5-difluorobenzene "core" is capable of giving organic photovoltaic cells (or solar cells) with the highest efficiency equal to 10.97%.

Bo Z. et al, in Nature Communications (2019), Vol. 10, p. 3038-3047, report non-fullerene electron acceptor compounds having a core of non-covalent fused rings terminated with two dicyanoindanone molecules capable of giving organic photovoltaic cells (or solar cells) with efficiencies up to 13.24%.

In order to capture a greater amount of light, ternary organic photovoltaic cells (or solar cells) are also of considerable interest as reported, for example, by Chang L. et al., In Organic Electronics (2021), Vol. 90, 106063, wherein the photoactive layer consists of three compounds, having complementary absorption spectra. Unlike binary photovoltaic cells (or solar cells), ternary photovoltaic cells (or solar cells) contain a third compound (which can be both donor and acceptor), which can be used in smaller quantities than the other two. There are various principles useful for the selection of the third compound such as, for example, (1) absorption complementary to the spectrum of the original binary mixture, in order to absorb the greatest number of photons; (2) appropriate values of the HOMO and LUMO energy levels, i.e. they must be arranged in cascade as seen for binary photovoltaic cells (or solar cells) so that the excitons can be effectively separated; (3) good compatibility in order to improve the morphology of the photoactive layer (as reported, for example, by Yang C. et al., in Organic Electronics (2021), Vol. 91, 106085). The addition of said third compound can lead to an improvement in the performance of the organic photovoltaic cells (or solar cells) and to greater stability. The organic photovoltaic cells (or solar cells) comprising non-fullerene electron acceptor compounds, can be of three types: D-FA-NFA, D-NFA-NFA, D-D-NFA, wherein D = electron donor compound, FA = fullerene electron acceptor compound, NFA = non-fullerene electron acceptor compound).

Examples of quaternary photovoltaic cells (or solar cells) are reported, for example, by Bi Z. et al., in Advanced Functional Materials (2019), Vol. 29, 1806804; or by Vincent P. et al., in Energies (2019), Vol. 12, 1838; or by Li W. et al., in Macromolecular Rapid Communications (2019), Vol. 40, Issue 21, 190353. Since organic photovoltaic devices (or solar devices), in particular the so- called emerging organic photovoltaic cells (or solar cells), are the subject of continuous research and studies, the study of new non-fullerene electron acceptor compounds having simple structure and easy synthetic preparation, it is still of great interest.

The Applicant therefore posed the problem of finding new non-fullerene electron acceptor compounds having a simple structure and easily synthesized, capable of being advantageously used in organic photovoltaic devices (or solar devices), in particular in binary, ternary, quaternary, organic photovoltaic cells (or solar cells), having both simple and tandem architecture.

The Applicant has now found that the benzoheterodiazole compounds disubstituted with dithienopyrrole groups having the specific general formula (I) reported below can be advantageously used as non-fullerene electron acceptors in organic photovoltaic devices (or solar devices), in particular in polymeric organic photovoltaics cells (or solar cells). Furthermore, said benzoheterodiazole compounds disubstituted with dithienopyrrole groups having general formula (I) are easy to synthesize and have good values of optical energy gap (E _g °) and maximum absorption (X max) in solution, good values of energy levels HOMO (EHOMO) and LUMO (ELUMO) and of electrochemical band-gap (E _gap Ec), as well as a good solubility in aromatic solvents. Furthermore, said benzoheterodiazole compounds disubstituted with dithienopyrrole groups having general formula (I) can be used as electron acceptor compounds with electron donor compounds having suitable energy levels, i.e. energy levels such as to obtain values of AELUMO, D A and of AEHOMO, D-A greater than zero and in any case greater than a threshold value which depends on the pair of electron donor compound (D) - electron acceptor compound (A). In particular, said benzoheterodiazole compounds disubstituted with dithienopyrrole groups having general formula (I) have the following values of the energy levels HOMO (EHOMO) and LUMO (ELUMO): -5.6 <E HOMO < -5.3 and -3,9 <E LUMO<-3,6 and are, therefore, suitable for use with electron acceptor compounds having higher HOMO (EHOMO) and LUMO (ELUMO) energy levels. Furthermore, said benzoheterodiazole compounds disubstituted with dithienopyrrole groups having general formula (I) can be advantageously used in organic photovoltaic cells (or solar cells), in particular in binary, ternary, quaternary, organic photovoltaic cells (or solar cells), having both simple and tandem architecture. Furthermore, said benzoheterodiazole compounds disubstituted with dithienopyrrole groups having general formula (I) can be advantageously used in perovskite-based photovoltaic cells (or solar cells) in the layer based on electron transport material (Electron Transport Layer - ETL). Furthermore, said benzoheterodiazole compounds disubstituted with dithienopyrrole groups having general formula (I) can be advantageously used in the construction of organic thin film transistors (OTFTs), or of organic field effect transistors (OFETs).

The object of the present invention is therefore a benzoheterodiazole compound disubstituted with dithienopyrrole groups having general formula (I): wherein:

Z represents a sulfur atom, an oxygen atom, a selenium atom; or an NR3 group wherein R3 is selected from C1-C30, preferably C1-C20, linear or branched alkyl groups, or from optionally substituted aryl groups;

Ri, equal to or different from each other, represent a hydrogen atom; or are selected from C1-C30, preferably C1-C20, linear or branched, optionally containing heteroatoms alkyl groups, optionally substituted aryl groups;

R2, equal to or different from each other, are selected from C8-C30, preferably C8-C24, branched, optionally containing heteroatoms alkyl groups, aryl groups substituted with -COOR4 or -OCOR4 groups wherein R4 is selected from C1-C30, preferably C1-C20, linear or branched, optionally containing heteroatoms alkyl groups, thioether groups R5-S-R6 wherein R5 and Re, equal to or different from each other, are selected from C1-C30, preferably C1-C20, linear or branched, optionally containing heteroatoms alkyl groups; A represents an electron acceptor group having general formula (II): wherein Xi and X2, equal to or different from each other, represent a hydrogen atom, or a halogen atom such as, for example, chlorine, fluorine, bromine, preferably chlorine, fluorine; or are selected from C1-C30, preferably C1-C20, linear or branched, optionally containing heteroatoms alkyl groups, C1-C30, preferably C1-C20, linear or branched, optionally substituted alkoxyl groups, -COOR7 ester groups wherein R7 is selected from C1-C30, preferably C1-C20, linear or branched optionally containing heteroatoms alkyl groups, C1-C30, preferably C1-C20, linear or branched, optionally substituted alkoxyl groups.

For the purpose of the present description and of the following claims, the definitions of the numerical ranges always include the extremes unless otherwise specified.

For purposes of the present description and of the following claims, the term "comprising" also includes the terms "which essentially consists of" or "which consists of".

For the purpose of the present description and of the following claims, the term "C1-C30 alkyl groups" and "C8-C30 alkyl groups" refers to linear or branched alkyl groups having from 1 to 30 carbon atoms, or having from 8 to 30 carbon atoms, branched, respectively. Specific examples of C1-C30 or C8-C30 alkyl groups are: methyl, ethyl, n-propyl, Ao-propyl, n-butyl, Ao-butyl, /-butyl, pentyl, 2-ethyl- hexyl, hexyl, heptyl, n-octyl, nonyl, decyl, dodecyl, 2-octyldodecyl, 2-butyloctyl, 3,7-dimethyloctyl, 2-octyldecyl, 2-hexyldecyl.

For the purpose of the present description and of the following claims, the term "C1-C30 alkyl groups optionally containing heteroatoms" and "C8-C30 alkyl groups optionally containing heteroatoms" means linear or branched alkyl groups having from 1 to 30 carbon atoms, or having from 8 to 30 carbon atoms, branched, respectively, wherein at least one of the hydrogen atoms is substituted with a heteroatom selected from: halogens such as, for example, fluorine, chlorine, preferably fluorine; nitrogen; sulfur; oxygen. Specific examples of C1-C30 or Cs- C30 alkyl groups optionally containing heteroatoms are: fluoromethyl, difluoromethyl, trifluoromethyl, trichloromethyl, 2,2,2-trifluoroethyl, 2,2,2- trichlororoethyl, 2,2,3,3-tetrafluoropropyl, 2,2,3,3,3-pentafluoropropyl, perfluoropentyl, perfluorooctyl, perfluorodecyl, perfluorododecyl, oxymethyl, thiomethyl, thioethyl, dimethylamino, propylamino, dioctylamino.

For the purpose of the present description and of the following claims, the term "aryl groups" refers to aromatic carbocyclic groups having from 6 to 60 carbon atoms. Said aryl groups can optionally be substituted with one or more groups, equal to or different from each other, selected from: halogen atoms such as, for example, fluorine, chlorine, preferably fluorine; hydroxyl groups; C1-C30 alkyl groups; C1-C30 alkoxyl groups; cyano groups; amino groups; nitro groups; aryl groups, phenoxy groups. Specific examples of aryl groups are: phenyl, methylphenyl, 2,5-dimethylphenyl, 2,6-dimethylphenyl, 2,4,6-triphenoxylphenyl, trimethylphenyl, di-zso-propylphenyl, Z-butylphenyl, methoxyphenyl, hydroxyphenyl, 2-phenoxyphenyl, fluorophenyl, pentafluorophenyl, chlorophenyl, nitrophenyl, dimethylaminophenyl, naphthyl, phenylnaphthyl, phenanthrene, anthracene.

For the purpose of the present description and of the following claims, the term "Ci -C30 alkoxyl groups" means linear or branched alkoxyl groups having from 1 to 30 carbon atoms. Said alkoxyl groups can optionally be substituted with one or more groups, equal to or different from each other, selected from: halogen atoms such as, for example, fluorine, chlorine, preferably fluorine; hydroxyl groups; C1-C30 alkyl groups; C1-C30 alkoxyl groups ; cyano groups; amino groups; nitro groups. Specific examples of C1-C30 alkoxyl groups are: methoxy, ethoxy, fluoroethoxy, zz-propoxy, zso-propoxy, zz-butoxy, zz-fluoro-butoxy, zso-butoxy, t- butoxy, pentoxy, hexyloxy, heptyloxy, octyloxy, nonyloxy, decyloxy, dodecyloxy.

According to a preferred embodiment of the present invention, in said general formula (I):

Z represents a sulfur atom; Ri, equal to each other, represent a C1-C30 alkyl group, preferably 2- ethylhexyl, n-undecyl, 4-octylphenyl; 2-butylphenyl;

R2, equal to each other, represent a branched C8-C30 alkyl group, preferably 2-octyldodecyl, 2-butyloctyl; or represent an aryl group substituted with -COOR4 groups wherein R4 represents a C1-C30 alkyl group, preferably 2- octyldodecyl, said -COOR4 group being in position 2, in position 3, or in position 4, of phenyl;

A represents an electron acceptor group having general formula (II) wherein Xi and X2, equal to each other, represent a hydrogen atom, or a fluorine or a chlorine atom.

Specific examples of benzoheterodiazole compounds disubstituted with dithienopyrrole groups having general formula (I) useful for the purpose of the present invention are reported in Table 1.

Table 1

GS028

The benzoheterodiazole compounds disubstituted with dithienopyrrole groups having general formula (I) object of the present invention can be obtained by processes known in the art. For example, if in the general formula (I) the substituent R2 represents an aryl group, the aforementioned benzoheterodiazole compounds disubstituted with dithienopyrrole groups can be obtained as reported, for example, in the international patent application WO 2016/046319 in the name of the Applicant and incorporated herein by reference.

When the substituent R2 in the general formula (I) represents an alkyl group, the aforementioned benzoheterodiazole compounds disubstituted with dithienopyrrole groups can be obtained starting from 4,7-dibromo-5,6- dialkoxybenzothiadiazole (3) which can be obtained starting from 4,7-dibromo- 5,6-difluorobenzothiadiazole (1) which is reacted at 50°C, in the presence of a solvent [for example, tetrahydrofuran (THF)], with sodium 2-octyldodecylate (2), obtained by the in situ reaction of 2-octyldecyl alcohol with sodium hydride (NaH) (Scheme 1) [Park T. et al., in Journal of the American Chemical Society (2017), Vol. 139, p. 12175-12181],

Scheme 1

Dithienopyrrole is a commercially available product but, for the purpose of the present invention, it has been synthesized from 3,3'-dibromo-2,2’-thiophene by the Buchwald-Hartwig amination reaction [Shi M. et al., Polymer (2011), Vol 52, p. 2559-2564], in the presence of palladium catalysts, with 2-ethylhexylamine. The reaction requires the presence of a stoichiometric amount of a base, usually sodium tert-butoxide, and bulky ligands [e.g., rac-2,2'-(bis-diphenylphosphino)- l,l'-binaphthyl (BINAP)].

For the purpose of the present invention, 3,3'-dibromo-2,2'-dithiophene (4) is reacted with 2-ethylhexylamine (5), in the presence of a palladium catalyst (0) (Pd2dbas), of a base [sodium terZ-butoxide-(tert-BuONa))] and of a bulky ligand [bidentate phosphine ligand - Xantphos], to give V-2-clhylhcxyldilhicnylpyrrolc (6) (Scheme 2).

Scheme 2

(4) tert-BuONa Pd ₂ dba ₃ 1 xantphos (6) toluene

In particular, in order to obtain the dialkoxybenzoheterodiazole compounds disubstituted with dithienopyrrole groups (GS016, GS017 and GS028), 5,6-di-2- octyldodecyloxy-4,7-dibromo-benzothiadiazole (3) is reacted with N-2- ethylhexyl-2-tributylstannyldithienopyrrole (7), by means of the Stille reaction, in the presence of Pd (II) or Pd (0) palladium catalysts such as, for example, Pd(PPhs)4 [Ding L. et al., Angewandte Chemie Int. Ed., (2012), Vol. 51, p. 9038- 9041], Pd(OAc) ₂ [Xie Y.-X. et al., Tetrahedron (2006), Vol. 62, p. 31-38], Pd(PPh3)2Ch [Caccialli F. et al., Chemical Communications (2011), Vol. 47, p. 8820-8822], Pd2dba3/P(o-tol) 3 [Reynolds J. R. et al., Journal of American Chemical Society (2012), Vol. 134, p. 2599 - 2612]. For the purpose of the present invention, the pair consisting of Pd2dba3/P(o-tol)3 was used as catalyst, obtaining 4,7-di(2-thienopyrrole)-5,6-di(2-octyldodecyloxy)phenoxy]ben zothiadiazole (8) (Scheme 3): the reaction was carried out in toluene, at 110°C, and the compound obtained at the end of the reaction was isolated by elution on a silica gel chromatographic column. A-2-ethylhexyl-2-tributylstannyldithienopyrrole (7) used as a reagent, must be previously prepared by metalation reaction of N-2- ethylhexyldithienylpyrrole (6) obtained as described above: said reaction was carried out in tetrahydrofuran, at -78°C, in the presence of a stoichiometric quantity of a base which can be selected, for example, between n-butyllithium (n- BuLi) (Kawabata K. et al., Macromolecules (2013), Vol. 46, p. 2078-2091), lithium diisopropylamide (LDA) (Wu Y. et al., Journal of Material Chemistry (2012), Vol. 22, p. 21362-21365). For the purpose of the present invention n- butyllithium (n-BuLi) (1.6 M solution in hexane) was used. The lithium salt thus obtained was reacted directly with tri-n-butylstannyl chloride to give N-(2- ethylhexyl)-2-tributylstannylthienothiophene (7): at the end of the reaction, the reaction mixture obtained was washed with a saturated aqueous solution of sodium bicarbonate. After having removed the solvent, by distillation at reduced pressure, V-(2-ethylhexyl)-2-tributylstannylthienothiophene (7) was used, without any purification, in the Stille reaction (Scheme 3).

Scheme 3

4,7-di-2-(V-2-ethylhexyldithienopyrrole)-5,6-di(2-octyldo decyloxy)- phenoxy] benzo thiadiazole (8) obtained as described above was subjected to formylation by means of the Vilsmeier-Haak reaction, [Lee J. K. et al., Journal of Photochemistry and Photobiology A: Chemistry (2014), Vol. 275, p. 47-53], obtaining 4,7-di-2-(V-2-ethylhexyl-5-formyldithienopyrrole)-5,6-di(2-o ctyl- dodecyloxyjbenzothiadiazole (9). The formylating agent was prepared in situ through the reaction of V,V-dimethylformamide (DMF) and phosphorus oxychloride (POCI3) to give the iminium ion: at the end of the reaction, the reaction mixture obtained was subjected to aqueous quenching in the presence of potassium acetate to hydrolyze the species formed by the electrophilic attack and thus give the corresponding aldehyde, as reported in Scheme 4.

Scheme 4 The formylating agent, obtained in situ according to the reaction reported in Scheme 5, was reacted with 4,7-di-2-(V-2-ethylhexyldithienopyrrole)-5,6-di(2- octyldodecyloxy)phenoxy]benzothiadiazole (8), in the presence of a solvent [for example, chloroform (CHCh)] (Lee J. et al., Journal of Photochemistry And Photobiology. A: Chemistry (2014), Vol. 275, p. 47- 53), obtaining 4,7-di-2-(V-2- ethylhexyl-6-formyldithienopyrrole)-5,6-di(2-octyldodecyloxy )benzothiadiazole (9) after quenching with an aqueous solution of potassium acetate and purification by elution on a silica gel chromatographic column (Scheme 5).

Scheme 5

4,7-di-2-(V-2-ethylhexyl-5-formyldithienopyrrole)-5,6-di( 2-octyl- dodecyloxy)benzothiadiazole (9) obtained as reported in Scheme 5, was reacted with active methylene compounds, by means of the Knovenagel reaction [Gao C. et al., Dyes and Pigments (2020), Vol. 178, 108388]: in particular, with 3- (dicyanomethylidene)indan-l-one (10), with 5,6-difluoro-3-(dicyano- methylidene)indan-l-one (11) and with 5,6-dichloro-3- (dicyanomethylidene)indan-l-one (39), which by reaction, in the presence of chloroform (CHCI3), in a basic environment in the presence of an excess of anhydrous pyridine (py), and the elimination of the air present in the reaction environment by means of vacuum/argon cycles, give, respectively, the compounds GS016, GS017 and GS028 (Scheme 6):

Scheme 6

GS028

In order to synthesize the compound GS018, 4,7-dibromo-5,6- difluorobenzothiadiazole (1) was reacted with 2-octyldodecyl 3 -hydroxybenzoate (14), in a basic environment, to give the nucleophilic substitution reaction, wherein the fluorine atoms are easily replaced with a nucleophile, in this case the phenate ion, prepared in situ by the reaction of a phenol with a base such as, for example, potassium carbonate (K2CO3), to give 4,7-dibromo-5,6-di(3-carbo(2- octyldodecyloxy)phenoxy)benzothiadiazole (15) (Scheme 7). The reaction is carried out in dipolar aprotic solvents, such as A,A-di methyl formamide (DMF). These solvents, allowing a greater separation between the nucleophile (phenate) and its counterion (potassium), are able to increase the reactivity of the nucleophile itself. The same effect can be obtained using the crown ethers, which coordinate the potassium away from the phenate, and by that increasing the reactivity of the nucleophile as reported, for example in the international patent application WO 2019/138332 in the name of the Applicant and incorporated herein by reference.

Scheme 7

2-octyldodecyl 3 -hydroxybenzoate (14), used in the nucleophilic substitution reaction, a commercially unavailable product, was obtained starting from potassium 3 -hydroxybenzoate, obtained in situ by treatment of 3- hydroxybenzoic acid (12) with potassium bicarbonate (KHCO3), by alkylation with 2-octyldodecylbromide (13). The potassium bicarbonate (KHCO3) allows the salification of the carboxylic acid only and not of the phenol: in this way, only the esterification is obtained and not the etherification. The reaction is carried out at 82°C, in a dipolar aprotic solvent such as, for example, A,A-di methyl formamide (DMF) (Scheme 8).

The compound GS018 can subsequently be obtained starting from 4,7- dibromo-5,6-di(3-carbo(2-octyldodecyloxy)phenoxy)benzothiadi azole (15), operating in the same way as described above for the synthesis of the compound GS017.

Scheme 9 reports the complete synthesis of the compound GS018.

Similarly, the compound GS019 can be synthesized starting from 4- hydroxybenzoic acid (18) (Scheme 10). Scheme 10

Similarly, the compound GS020 can be synthesized starting from 2- hydroxybenzoic acid (23) (Scheme 11).

Scheme 11

The compound GS022 was synthesized by operating in a similar way to the synthesis of the compound GS017 reported above, suitably substituting the reagents. For this purpose, for the synthesis of the compound GS022, undecylamine and 2-butyloctanol were used instead of 2-ethylhexylamine and 2-octyldodecanol (Scheme 12).

Scheme 12

Further details relating to the processes for the preparation of said benzoheterodiazole compounds disubstituted with dithienopyrrole groups having general formula (I) can be found in the following examples. As described above, said benzoheterodiazole compound disubstituted with dithienopyrrole groups having general formula (I) can be advantageously used as an electron acceptor compound in organic photovoltaic devices (or solar devices), selected, for example, from binary, ternary, quaternary, organic photovoltaic cells (or solar cells), having simple or tandem architecture, organic photovoltaic modules (or solar modules), both on a rigid support and on a flexible support.

Consequently, a further object of the present invention is an organic photovoltaic device (or solar device) selected, for example, from binary, ternary, quaternary, organic photovoltaic cells (or solar cells), having simple or tandem architecture, organic photovoltaic modules (or solar modules), both on a rigid support and on a flexible support, comprising at least one benzoheterodiazole compound disubstituted with dithienopyrrole groups having general formula (I), preferably binary, ternary, quaternary, organic photovoltaic cell (or solar cell), having simple or tandem architecture.

According to a preferred embodiment of the present invention, said binary, ternary, quaternary, organic photovoltaic cell (or solar cell), having simple or tandem architecture, comprises: at least one rigid or flexible support; an anode; at least one layer of photoactive material; a cathode; wherein said layer of photoactive material comprises at least one photoactive organic polymer as electron donor compound, at least one benzoheterodiazole compound disubstituted with dithienopyrrole groups having general formula (I) as electron acceptor compound.

According to a preferred embodiment of the present invention, said photoactive organic polymer can be selected, for example, from:

(a) polythiophenes such as, for example, regioregular poly(3 -hexylthiophene) (P3HT), poly (3 -octylthiophene), poly(3,4-ethylenedioxythiophene), or mixtures thereof;

(b) alternating or statistical conjugated copolymers comprising:

-at least one benzotriazole unit (B) having general formula (la) or (lb): wherein R group is selected from alkyl groups, aryl groups, acyl groups, thioacyl groups, said alkyl, aryl, acyl and thioacyl groups being optionally substituted;

-at least one conjugated structural unit (A), wherein each unit (B) is connected to at least one unit (A) in any of the positions 4, 5, 6, or 7, preferably in the positions 4 or 7;

(c) alternating conjugated copolymers comprising benzothiodiazole units such as, for example, PCDTBT {poly[N-9"-heptadecanyl-2,7-carbazole-alt-5,5- (4 ',7 '-di-2-thienyl-2 ', 1 ', 3 '-benzothiadiazole] } , PCPDTBT { poly [2,6-(4,4- Z>zs-(2-ethylhexyl)-4H-cyclopenta[2,l-b;3,4-b']-dithiophe ne)-aZz-4,7-(2,l,3- benzotiadiazole)] } ;

(d) alternating conjugated copolymers comprising thieno[3,4-b]pyrazine units;

(e) alternating conjugated copolymers comprising quinoxaline units;

(f) alternating conjugated copolymers comprising silol monomer units such as, for example, 9,9-dialkyl-9-silafluorene copolymers;

(g) alternating conjugated copolymers comprising condensed thiophene units such as, for example, thieno [3, 4-b] thiophene and benzo[l,2-b:4,5- b'] dithiophene copolymers;

(h) alternating conjugated copolymers comprising benzothiodiazole or naphthothiadiazole units substituted with at least one fluorine atom and thiophene units substituted with at least one fluorine atom such as, for example, PffBT4T-2OD {poly[(5,6-difluoro-2,l,3-benzothiadiazole-4,7- diyl)-aZt-(3,3'''-di(2-octyldodecyl)-2,2',5',2'';5'',2'"-qua terthiophene-5,5'''- diyl)] }, PBTff4T-2OD {poly[(2,l,3-benzothiadiazole-4,7-diyl)-alt-(4',3"- difluoro-3,3'"-di(2-octyldodecyl)-2,2';5',2";5",2'"-quaterth iophene-5,5'"- diyl)]}, PNT4T-2OD {poly(naphtho[l,2-c:5,-c']bis[l,2,5]thiadiazole-5,10- diyl)-alt-(3,3"'-di(2-octyldodecyl)-2,2';5',2";5",2"'-quater thiophene-5,5"'- diyl)]};

(i) conjugated copolymers comprising thieno[3,4-c]pyrrole-4, 6-dione units such as, for example, PBDTTPD {poly[[5-(2-ethylhexyl)-5,6-dihydro-4,6- dioxo-4H-thieno[3,4-c]pyrrole-l,3-diyl] [4,8-bis:[(2- ethylhexyljoxy ] benzo [l,2-b:4,5-b'] dithiophene-2 , 6 -diyl ] } ;

(1) conjugated copolymers comprising thienothiophene units such as, for example, PTB7 {poly({4,8-bis[(2-ethylhexyl)oxy]benzo[l,2-b:4,5- b '] dithiophene-2, 6 -diyl } { 3 -fluoro-2- [(2-ethylhexyl)carbonyl] thieno [3 ,4- b]thiophenediyl}}, PBDB-T polymer poly[[4,8-bis[5-(2-ethylhexyl)-2- thienyl]benzo[l,2-b:4,5-b']dithiophene-2,6-diyl]-2,5-thiophe nediyl[5,7- bis(2-ethylhexyl)-4,8-dioxo-4H,8H-benzo[l,2-c:4,5-c']dithiop hene-l,3- diyl] -2 , 5 -thiophenediyl] ;

(m) polymers comprising an indacen-4-one derivative having general formula (III), (IV) or (V): wherein:

- W and W i, equal to or different from each other, preferably equal to each other, represent an oxygen atom; a sulfur atom; an NR3 group wherein R3 represents a hydrogen atom, or is selected from C1-C20, preferably C2-C10, linear or branched alkyl groups;

- Z and Y, equal to or different from each other, preferably equal to each other, represent a nitrogen atom; or a CR4 group, wherein R4 represents a hydrogen atom, or is selected from C1-C20, preferably C2-C10, linear or branched alkyl groups, optionally substituted cycloalkyl groups, optionally substituted aryl groups, optionally substituted heteroaryl groups, C1-C20, preferably C2-C10, linear or branched alkoxyl groups, polyethyleneoxyl groups R5-CHCH2-CH2- O] _n - wherein R5 is selected from C1-C20, preferably C2-C10, linear or branched alkyl groups, and n is an integer comprised between 1 and 4, -R6-OR7 groups wherein Re is selected from C1-C20, preferably C2-C10, linear or branched alkylene groups and R7 represents a hydrogen atom or is selected from C1-C20, preferably C2-C10, linear or branched alkyl groups, or is selected from polyethyleneoxyl groups Rs-[-OCH2-CH2-]n- wherein R5 has the same meanings reported above and n is an integer comprised between 1 and 4, -CORs groups wherein Rs is selected from C1-C20, preferably C2-C10, linear or branched alkyl groups, -COOR9 groups wherein R9 is selected from C1-C20, preferably C2-C10, linear or branched alkyl groups; or represent a -CHO group, or a cyano group (-CN);

- Ri and R2, equal to or different from each other, preferably equal to each other, are selected from C1-C20, preferably C2-C10, linear or branched alkyl groups; optionally substituted cycloalkyl groups; optionally substituted aryl groups; optionally substituted heteroaryl groups; C1-C20, preferably C2-C10, linear or branched alkoxyl groups; polyethyleneoxyl groups Rs-O-[CH2-CH2-O]n- wherein R5 has the same meanings reported above and n is an integer comprised between 1 and 4; -R6-OR7 groups wherein Re and R7 have the same meanings reported above; -CORs groups wherein Rs has the same meanings reported above; -COOR9 groups wherein R9 has the same meanings reported above; or represent a -CHO group, or a cyano group (-CN);

- D represents an electron donor group;

- A represents an electron acceptor group;

- n is an integer comprised between 10 and 500, preferably comprised between 20 and 300;

(n) polymers comprising anthradithiophene derivatives having general formula (X): wherein:

- Z, equal to or different from each other, preferably equal to each other, represent a sulfur atom, an oxygen atom, a selenium atom; - Y, equal to or different from each other, preferably equal to each other, represent a sulfur atom, an oxygen atom, a selenium atom;

- Ri, equal to or different from each other, preferably equal to each other, are selected from amino groups -NR3R4 wherein R3 represents a hydrogen atom, or is selected from C1-C20, preferably C2-C10, linear or branched alkyl groups, or is selected from optionally substituted cycloalkyl groups and R4 is selected from C1-C20, preferably C2-C10, linear or branched alkyl groups, or is selected from optionally substituted cycloalkyl groups; or are selected from C1-C30, preferably C2-C20, linear or branched alkoxyl groups; or are selected from polyethyleneoxyl groups Rs-O-[CH2-CH2-O]n- wherein R5 is selected from C1-C20, preferably C2-C10, linear or branched alkyl groups, and n is an integer comprised between 1 and 4; or are selected from -Rf>- OR7 groups wherein Re is selected from C1-C20, preferably C2-C10, linear or branched alkylene groups and R7 represents a hydrogen atom, or is selected from C1-C20, preferably C2-C10, linear or branched alkyl groups, or is selected from polyethyleneoxyl groups Rs-[-OCH2-CH2-]n- wherein Rs has the same meanings reported above and n is an integer comprised between 1 and 4; or are selected from thiol groups -SRs wherein Rs is selected from C1-C20, preferably C2-C10, linear or branched alkyl groups;

- R2, equal to or different from each other, preferably equal to each other, represent a hydrogen atom; or are selected from C1-C20, preferably C2-C10, linear or branched alkyl groups; or are selected from -COR9 groups wherein R9 is selected from C1-C20, preferably C2-C10, linear or branched alkyl groups; or are selected from -COOR10 groups wherein Rio is selected from C1-C20, preferably C2-C10, linear or branched alkyl groups; or are selected from optionally substituted aryl groups; or are selected from optionally substituted heteroaryl groups;

A represents an electron acceptor group; n is an integer comprised between 10 and 500, preferably comprised between 20 and 300.

Further details relating to alternating or statistical conjugated copolymers (b) comprising at least one benzotriazole unit (B) and at least one conjugated structural unit (A) and to the process for their preparation can be found, for example, in the international patent application WO 2010 /046114 in the name of the Applicant.

Further details relating to alternating conjugated copolymers comprising benzothiodiazole units (c), alternating conjugated copolymers comprising thieno[3,4-b]pyrazidine units (d), alternating conjugated copolymers comprising quinoxaline units (e), alternating conjugated copolymers comprising silolic monomer units (f), alternating conjugated copolymers comprising condensed thiophenic units (g), can be found, for example, in Chen J. et al., Accounts of Chemical Research (2009), Vol. 42, No. 11, p. 1709-1718; Pd R. et al., Macromolecules (2015), Vol. 48 (3), p. 453-461.

Further details relating to alternating conjugated copolymers comprising benzothiodiazole or naphthothiadiazole units substituted with at least one fluorine atom and thiophene units substituted with at least one fluorine atom (h) can be found, for example, in Liu Y. et al, Nature Communications (2014), Vol. 5, Article no. 5293 (DOI:10.1038/ncomms6293).

Further details relating to conjugated copolymers comprising thieno[3,4- c]pyrrole-4, 6-dione (i) units can be found, for example, in Pan H. et al, Chinese Chemical Letters (2016), Vol. 27, Issue 8, p. 1277-1282.

Further details relating to conjugated copolymers comprising thienothiophene units (1) can be found, for example, in Liang Y. et al., Journal of the American Chemical Society (2009), Vol. 131(22), p. 7792-7799; Liang Y. et al, Accounts of Chemical Research (2010), Vol. 43(9), p. 1227-1236.

Further details relating to polymers comprising an indacen-4-one (m) derivative can be found, for example, in the international patent application WO 2016/180988 in the name of the Applicant.

Further details relating to polymers comprising anthradithiophene derivatives having general formula (X) (n) can be found, for example, in the international patent application WO 2019/175367 in the name of the Applicant.

According to a preferred embodiment of the present invention, in the case of a ternary organic photovoltaic cell (or solar cell), having simple or tandem architecture, the photoactive layer can comprise, for example: two photoactive organic polymers selected from those reported above and a benzoheterodiazole compound disubstituted with dithienopyrrole groups having general formula (I); or a photoactive organic polymer selected from those reported above and two benzoheterodiazole compounds disubstituted with dithienopyrrole groups having general formula (I); or a photoactive organic polymer selected from those reported above, a benzoheterodiazole compound disubstituted with dithienopyrrole groups having general formula (I) and a fullerene derivative such as, for example (6, 6)-phenyl-C6i -butyric acid methyl ester (PC61BM), (6,6)-phenyl-C?i- butyric acid methyl ester (PC71BM); or a photoactive organic polymer selected from those reported above, a benzoheterodiazole compound disubstituted with dithienopyrrole groups having general formula (I) and a non-fullerene compound selected, for example, from non-fullerene compounds, optionally polymeric, such as, for example, compounds based on perylene-diimides or naphthalene-diimides and fused aromatic rings; indacenothiophenes with electron-poor terminal groups; compounds having an aromatic core able to rotate symmetrically, for example, derivatives of corannulene or truxenone.

According to a preferred embodiment of the present invention, in the case of a quaternary organic photovoltaic cell (or solar cell), having simple or tandem architecture, the photoactive layer can comprise, for example: two photoactive organic polymers selected from those reported above and two benzoheterodiazole compounds disubstituted with dithienopyrrole groups having general formula (I); or two photoactive organic polymers selected from those reported above, a benzoheterodiazole compound disubstituted with dithienopyrrole groups having general formula (I), and a fullerene derivative such as, for example (6, 6)-phenyl-C6i -butyric acid methyl ester (PC61BM), (6,6)-phenyl-C?i- butyric acid methyl ester (PC71BM); or two photoactive organic polymers selected from those reported above, a benzoheterodiazole compound disubstituted with dithienopyrrole groups having general formula (I) and a non-fullerene compound selected, for example, from non-fullerene compounds, optionally polymeric, such as, for example, compounds based on perylene-diimides or naphthalene-diimides and fused aromatic rings; indacenothiophenes with electron-poor terminal groups; compounds having an aromatic core capable of symmetrically rotating, for example, derivatives of corannulene or truxenone.

Specific examples of said non-fulllerene, optionally polymeric compounds are: 3,9-bis(2-methylene-[3-(l,l-dicyanomethylene)-6,7-difluoro)- indanone))- 5,5,l l,l l-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2',3'-d']-s-indacen o-[l,2-b:5,6- b ] -dithiophene, poly{ [N,W-bis(2-octyldodecyl)-l,4,5,8-naphthalene-diimide-2,6- diyl]-a/t-5,5'-(2,2'-bithiophene)}, 2,2'-((2Z,2'Z)-((4,4,9,9-tetrahexyl-4,9-dihydro- s-indacene[l,2-b: 5,6-b']dithiophene-2,7-diyl)bis(methanylidene))bis-(3-oxo-2, 3- dihydro-lH-indene-2,l-diylidene))dimalononitrile, 2,2'-[[6,6,12,12-tetrakis(4- hexylphenyl)-6,12-dihydrodithieno[2,3-< 2',3'-<7']-s-indaceno[l,2-Z 5,6- Zj']dithiophene-2,8-diyl]bis[methylidene(3-oxo-l/Z-indene-2, l(3/Z)-diylidene)]]- bis [propanodinitrile] (ITIC), ITIC-4F.

Further details relating to said non-fullerene compounds can be found, for example, in Nielsen C. B. et al., Accounts of Chemical Research (2015), Vol. 48, p. 2803-2812; Zhan C. et al., .RSC Advances. (2015), Vol. 5, p. 93002-93026; Lin Y. et al. Advanced Materials. (2015), Vol. 27, Issue 7, p. 1170-1174, reported above.

The aforementioned organic photovoltaic cell (or solar cell) can be obtained according to the processes known in the art reported above.

The present invention will now be illustrated in greater detail through an embodiment with reference to Figure 1 reported below.

Figure 1 represents a cross-sectional view of an organic photovoltaic cell (or solar cell) object of the present invention.

With reference to Figure 1, the organic photovoltaic cell (or solar cell) (1) having a bulk heterojunction architecture comprises: a transparent support (2) made of glass or plastic such as, for example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), polypropylene (PP), polyimide (PI), triacetyl cellulose (TAC), or copolymers thereof; an anode (3), preferably an indium tin oxide (ITO) anode; a layer of PEDOT:PSS [poly(3,4-ethylenedioxythiophene)polystyrene sulphonate] (4); a layer of photoactive material (5) comprising at least one photoactive organic polymer, at least one benzoheterodiazole compound disubstituted with dithienopyrrole groups having general formula (I); a cathodic buffer layer (6), preferably comprising lithium fluoride; a cathode (7), preferably an aluminum cathode.

As described above, said benzoheterodiazole compound disubstituted with dithienopyrrole groups having general formula (I) can be advantageously used in perovskite-based photovoltaic cells (or solar cells) in the layer based on electron transport material (Electron Transport Layer - ETL).

Consequently, a further object of the present invention is a perovskite-based photovoltaic cell (or solar cell) wherein the layer based on electron transport material (Electron Transport Layer - ETL) comprises at least one benzoheterodiazole compound disubstituted with dithienopyrrole groups having general formula (I).

As described above, said benzoheterodiazole compound disubstituted with dithienopyrrole groups having general formula (I) can be advantageously used in the construction of organic thin film transistors (OTFTs), or organic field effect transistors (OFETs).

Consequently, a further object of the present invention relates to organic thin film transistors (OTFTs), or organic field effect transistors (OFETs), comprising at least one benzoheterodiazole compound disubstituted with dithienopyrrole groups having general formula (I).

In the following examples, the analytical techniques and characterization methodologies listed below were used.

Spectra ¹ H-NMR

The ¹ H-NMR spectra were recorded with a nuclear magnetic resonance spectrometer mod. Bruker Avance 400, using deuterated chloroform (CDCI3) at 25°C and tetramethylsilane (TMS) (Merck) as internal standard. For this purpose, solutions of the benzoheterodiazole compounds disubstituted with dithienopyrrole groups having general formula (I) object of the present invention obtained according to the following examples, having concentrations equal to 10% by weight with respect to the total weight of the final solution, were used.

Absorption Spectra

The absorption spectra of the solutions in o-xylene or in dichlorobenzene of the benzoheterodiazole compounds disubstituted with dithienopyrrole groups having general formula (I) object of the present invention obtained according to the following examples, in the ultraviolet and in the visible (UV-Vis) (250 nm - 800 nm), were acquired in transmission using a dual beam spectrophotometer and dual monochromator X 950 Perkin Elmer, with a bandwidth of 2.0 nm and a step of 1.0 nm, using quartz cuvettes with an optical path equal to 1 cm. The respective optical energy gaps (E _g °) were also determined from these spectra, using the tangent method.

Determination of HOMO (EHOMO) and LUMP (ELUMO) energy levels

The determination of the values of HOMO (EHOMO) and LUMP (ELUMO) energy levels of the benzoheterodiazole compounds disubstituted with dithienopyrrole groups having general formula (I) object of the present invention obtained according to the following examples, was carried out using the cyclic voltammetry (CV) technique. With this technique it is possible to measure the values of the radical cation formation potentials and the radical anion formation potentials of the sample in question. From the values of the potentials thus obtained, it is possible to extrapolate the values of the HOMO (EHOMO) and LUMP (ELUMO) energy levels of the sample under examination (expressed in eV). The difference between the values of the HOMO (EHOMO) and LUMP (ELUMO) energy levels gives the value of the electrochemical band-gap (E _gap Ec).

The values of the electrochemical band-gap (E _gap Ec) are generally higher than the values of the optical energy-gap (E _g °) since during the execution of the cyclic voltammetry (CV), the neutral compound is charged and it undergoes a conformational reorganization, with an increase in the energy gap, while the optical measurement does not lead to the formation of charged species.

The cyclic voltammetry (CV) measurements were performed with an Autolab PGSTAT12 potentiostat (with GPES Ecochemie software) in a three- electrode cell. In the measurements carried out, an Ag/AgCl electrode was used as a reference electrode, a platinum wire as a counter electrode and a glassy graphite electrode as a working electrode. The sample to be analyzed was dissolved in a suitable solvent and, subsequently, it was deposited, with a calibrated capillary, on the working electrode, so as to form a film. The electrodes were immersed in a 0.1 M electrolytic solution of 95% tetrabutylammonium tetrafluoroborate in acetonitrile. The sample was subsequently subjected to a cyclic potential in the form of a triangular wave. At the same time, according to the applied potential difference, the current was monitored, which signals the occurrence of oxidation or reduction reactions of the species present.

The oxidation process corresponds to the removal of an electron from HOMO, while the reduction cycle corresponds to the introduction of an electron into the LUMO. The potentials for the formation of the radical cation and of the radical anion were obtained from the value of the peak onset (Eonset), which is determined by molecules and/or chain segments with (EHOMO)-(ELUMO) energy levels closer to the edges of the bands. The electrochemical potentials and those relating to the electronic levels can be correlated if both refer to the vacuum. For this purpose, the potential of ferrocene in vacuum, known in the literature and equal to -4.8 eV, was taken as a reference. The inter-solvent redox ferrocene/ferrocinium pair (Fc/Fc ⁺ ) was selected because it has an oxidationreduction potential independent of the working solvent.

The general formula for calculating the energies of the (EHOMO)-(ELUMO) energy levels is therefore given by the following equation:

E (eV) = -4.8 + [EI/ ₂ Ag/Agci (Fc/Fc ⁺ ) -E _on set Ag/Agci (compound)] wherein:

E = HOMO (EHOMO) or LUMO (ELUMO) energy level depending on the Eonset value entered;

EI/2 Ag/Agci = half-wave potential of the peak corresponding to the redox ferrocene/ferrocinium pair (Fc/Fc ⁺ ) measured under the same analysis conditions of the sample and with the same set of three electrodes used for the sample; Eonset Ag/Agci = onset potential measured for the compound in the anodic zone (oxidation) when you want to calculate the HOMO (EHOMO) energy level and in the cathodic zone (reduction) when you want to calculate the LUMO (ELUMO) energy level. EXAMPLE 1

Synthesis of compound GS016: 2,2'-5,6-bis(2-octyldodecyloxy)benzorciri,2,51- thiadiazole-4,7-di-2-(N-2-ethylhexyldithienopyrrole)-6-diyl- bis- (methanylylidene)-3-oxo-2.3-dihydro- l H-indcnc-2.1 -diylidcnc)diinalononitrilc Synthesis of 5,6-di(2-octyldodecyloxy)-4,7-dibromobenzothiadiazole (3)

In a 100 ml flask equipped with magnetic stirring, thermometer and condenser, in an inert atmosphere (argon), sodium hydride (NaH) (60% dispersion in mineral oil) (Merck) (188 mg; 4.7 mmol) was added in a single portion to a solution of 2-octyldodecanol (Merck) (1.48 g; 5.24 mmol) in anhydrous tetrahydrofuran (Merck) (20 ml): the reaction mixture obtained was heated at 50°C and kept, under stirring, at said temperature, for 3 hours. Subsequently, a solution of 4,7-dibromo-5,6-difluorobenzothiadiazole (1) (Merck) (700 mg; 2.12 mmol) in anhydrous tetrahydro furan (THF) (Merck) (10 ml) was added by dripping: the reaction mixture obtained was kept at 50°C, under stirring, for 18 hours. Subsequently, the reaction mixture was poured into distilled water (50 ml) and extracted with ethyl ether (Merck) (3 x 30 ml). The organic phase (obtained by combining the three organic phases) was washed to neutral with distilled water (3 x 30 ml) and dried over sodium sulphate (Merck). The solvent was removed by distillation under reduced pressure and the residue obtained was purified by elution on a silica gel chromatographic column (eluent: n-heptane (Merck)/dichloromethane (Merck) in a ratio of 95/5 v/v) obtaining 1.5 g (1.7 mmol) of 4,7-dibromo-5,6-di(2-octyldodecyloxy)benzothiadiazole (3) (yield = 80%).

Synthesis of A-(2-ethylhexyl)dithienopyrrole (6)

In a 100 ml flask equipped with magnetic stirring, thermometer and condenser, in an inert atmosphere (argon), the following were added, in order: 3,3’-dibromo-2,2'-dithiophene (4) (Merck) (948 mg; 2.9 mmol), sodium tert- butoxide (tert-BuONa) (Merck) (686.3 mg; 7.1 mmol), tris-dibenzylideneacetone dipalladium (Pd2dbas) (Merck) (66.7 mg; 0.07 mmol) and rac-2,2'-(bis- diphenylphosphino)-l,l'-binaphthyl (rac-BINAP) (97%) (Merck) (1.83 mg; 0.3 mmol) and, by dripping, a solution of 2-ethylhexylamine (5) (Merck) (421 mg; 3.25 mmol) in anhydrous toluene (Merck) (7.8 ml): after placing the flask in a preheated oil bath at 110°C, the reaction mixture was kept, under stirring, at said temperature, for 18 hours. Subsequently, after removing the flask from the oil bath, the temperature was allowed to drop spontaneously to 20°C and, after adding a saturated aqueous solution of sodium chloride (NaCl) (Merck) (20 ml), the reaction mixture was extracted with ethyl ether (Merck) (3 x 30 ml). The organic phase (obtained by combining the three organic phases) was washed to neutral with distilled water (3 x 30 ml) and dried over sodium sulphate (Merck). The solvent was removed by distillation under reduced pressure and the residue obtained was purified by elution on a silica gel chromatographic column (eluent: H-hcptanc (Merck)/dichloromethane (Merck) in a gradient from 95/5 to 90/10 v/v) obtaining 750 mg (2.6 mmoles) of A-(2-ethylhexyl)dithienopyrrole (6) (yield = 88%).

Synthesis of A-(2-ethylhexyl)-2-tributylstannyldithienopyrrole (7)

In a 100 ml flask equipped with magnetic stirring, thermometer and condenser, in an inert atmosphere (argon), placed in a dry ice/acetone bath, at -78°C, n-butyllithium (n-BuLi) [1.6 M solution in hexane (Merck) ] (1.7 ml; 2.7 mmol) was added by dripping over 10 minutes to a solution of N-(2- ethylhexyl)dithienopyrrole (6) (717 mg; 2.46 mmol) obtained as described above, in anhydrous tetrahydrofuran (Merck) (22 ml). Subsequently, the temperature was allowed to rise spontaneously to -50°C, in 3 hours. Subsequently, after bringing the temperature back to -78°C, tri-n-butylstannyl chloride (Merck) (0.8 ml; 2.95 mmols) was added by dripping: after 15 minutes the flask was removed from the dry ice bath, the temperature was allowed to rise spontaneously to 20°C and the reaction mixture was kept at said temperature, under stirring, for 12 hours. Subsequently, after adding a saturated aqueous solution of sodium bicarbonate (Merck) (20 ml), the reaction mixture was extracted with ethyl ether (Merck) (3 x 25 ml). The organic phase (obtained by combining the three organic phases) was washed with a saturated aqueous solution of sodium bicarbonate (Merck) (1 x 20 ml) and dried over sodium sulphate (Merck). The solvent was removed by distillation under reduced pressure obtaining A-(2-ethylhexyl)-2- tributylstannyldithienopyrrole (7) which was used as such in the subsequent reaction.

Synthesis of 4,7-di-2-(A-2-ethylhexyldithienopyrrole)-5,6-di(2-octydecylo xy)- benzothiadiazole (8)

In a 100 ml flask equipped with magnetic stirring, thermometer and condenser, in an inert atmosphere (argon), 4,7-dibromo-5,6-di(2- octyldodecyloxy)benzothiadiazole (3) (608 mg; 0.7 mmol) obtained as described above was added to a solution of A-(2-ethylhexyl)-2-tributylstannyldithieno- pyrrole (7) (2.46 mmol) obtained as described above, in anhydrous toluene (Merck) (20 ml). After removing the air present through 3 vacuum/nitrogen cycles, tris-dibenzylideneacetone dipalladium (Pd2dbas) (Merck) (18.3 mg; 0.02 mmol) and tris-o-tolylphosphine [P(o-tol)3] (Merck) (24.2 mg; 0.08 mmoles) were added: after having again removed the air present by means of 3 vacuum/nitrogen cycles, the flask was placed in an oil bath preheated to 108° C and the reaction mixture was kept, at said temperature, under stirring, for 12 hours. Subsequently, the reaction mixture was poured into distilled water (50 ml) and extracted with ethyl acetate (Merck) (3 x 50 mL). The organic phase (obtained by combining the three organic phases) was washed to neutral with distilled water (3 x 50 ml) and dried over sodium sulphate (Merck). After removing the solvent by distillation under reduced pressure, the residue obtained was purified by elution on a silica gel chromatographic column (eluent: n-heptane (Merck)/dichloromethane (Merck) in a gradient from 90/10 to 80/20 to 70/30 v/v), obtaining 806 mg (0.63 mmol) of 4,7-di-2-(A-2-ethylhexyldithienopyrrole)-5,6-di(2- octydecyloxy)benzo-thiadiazole (8) (yield = 90%).

Synthesis of 4,7-di-2-(A-2-ethylhexyl-5-formyldithienopyrrole)-5,6-di(2-o ctyl- dodecyloxy)benzothiadiazole (9)

In a 100 ml flask equipped with magnetic stirring, thermometer and condenser, in an inert atmosphere (argon), at 0°C, A,A-di methyl formamide (DMF) (Merck) (2 ml) and, by dripping, phosphorus oxychloride (POCI3) (Merck) (1.62 ml; 2.66 g; 17.3 mmol) were added to a solution of 4,7-di-2-(7V-2- ethylhexyldithienopyrrole)-5,6-di(2-octyldodecyloxy)benzothi adiazole (8) (806 mg; 0.63 mmol) obtained as described above, in anhydrous chloroform (CHCI3) (Merck) (25 ml): the reaction mixture was stirred and, after 30 minutes, was heated to 69°C and kept, under stirring, at said temperature, for 18 hours. After allowing the temperature to drop spontaneously to 20°C, a 10% solution of potassium acetate in water (20 ml) was added and the reaction mixture was kept, under stirring, at this temperature, for 1 hour and subsequently extracted with ethyl acetate (Merck) (3 x 30 ml). The organic phase (obtained by combining the three organic phases) was washed to neutral with distilled water (3 x 30 ml) and dried over sodium sulphate (Merck). After removing the solvent by distillation under reduced pressure, the residue obtained was purified by elution on a silica gel chromatographic column (eluent: n-heptane (Merck)/chloroform (Merck) in the ratio 1/1 v/v), obtaining 750 mg (0.55 mmol) of 4,7-di-2-(A-2-ethylhexyl-5- formyldithienopyrrole)-5,6-di(2-octyldodecyloxy)benzothiadia zole (9) (87.2% yield).

Synthesis of the compound GS016

In a 100 ml flask, equipped with magnetic stirring, thermometer and condenser, in an inert atmosphere (argon), 3-(dicyanomethylidene)indan- 1-one (10) (Merck) (145.5 mg; 0.75 mmol) was added to a solution of 4,7-di-2-(/V-2- ethylhexyl-5-formyldithienopyrrole)-5,6-di(2-octyldodecyloxy )benzothia- diazole (9) (247.6 mg; 0.18 mmol) obtained as described above, in anhydrous chloroform (CHCh) (Merck) (2 4 ml): after removing the air from the reaction environment, by means of 3 vacuum/argon cycles, anhydrous pyridine (py) (Merck) (1.2 ml) was added by dripping. After having again removed the air from the reaction environment by 3 vacuum/argon cycles, the reaction mixture was heated to 69°C and kept at said temperature for 12 hours, under stirring. Subsequently, the temperature was allowed to drop spontaneously to 20°C and ethanol (Merck) (15 ml) was added: the reaction mixture was kept at said temperature, for 20 minutes, under stirring. Subsequently, most of the organic solvent was removed by distillation at reduced pressure and the remaining residue was taken up with dichloromethane (Merck) (10 ml): the solution obtained was added, by dripping, to ethanol (Merck) (20 ml). The obtained precipitate was isolated by filtration, washed with ethanol (Merck) (5 x 10 ml), acetonitrile (Merck) (1 x 10 ml) and finally with ethyl ether (Merck) (1 x 10 ml) obtaining 250 mg (0.15 mmol) of the compound GS016 (yield = 81%).

The compound GS016 was subjected to ’H-NMR characterization by operating as described above.

’H-NMR (400 MHz, Chloroform- d) 5 8.95 (s, 2H), 8.68 (m, 2H), 8.49 (s, 2H), 7.91 (m, 2H), 7.82 (s. br., 2H), 7.72 (m, 4H), 4.20 (m, 4H), 4.10 (d, J = 6.8 Hz, 4H), 2.18 - 2.03 (m, 4H), 1.48 - 1.11 (m, 80H), 1.03 - 0.78 (m, 24H).

The compound GS016 was also subjected to the other characterizations reported above: the absorption spectrum was acquired from which the optical energy gap (Eg ⁰ ) was determined and the values of the energy levels HOMO (EHOMO), LUMO (ELUMO) and electrochemical band-gap (E _gap Ec) were determined: the values obtained are reported in Table 2 and in Table 3. Table 2 shows, in order: the compound, the solvent used, the value of the optical energy gap (Eg ⁰ ), expressed in (eV), the maximum value of the band at the lowest energy in the absorption spectrum [1 max (abs.)] expressed in (nm).

Table 3 shows, in order: the compound, the value of the energy level HOMO (EHOMO) expressed in (eV), the value of the energy level LUMO (ELUMO) expressed in (eV) and, finally the value of the electrochemical band-gap (E _gap Ec) expressed in (eV).

Figure 2 [the abscissa shows the potential (E) measured in volts (V) vs ferrocene/ferrocinium (Fc/Fc ⁺ ) and the ordinate shows the current density (i) measured in amperes (A)] shows the cyclic voltagram obtained by operating as described above.

EXAMPLE 2

Synthesis of the compound GS017: 2,2'-5,6-bis(2- octyldodecyloxy)benzo[c][l,2,51-thiadiazole-4,7-di-2-(N-2-et hylhexyldithieno- pyrrole)-6-diyl-bis-(methanylylidene)-5,6-difluoro-3-oxo-2,3 -dihydro-lH- indene-2, 1 -diylidene)dimalononitrile

Synthesis of the compound GS017

In a 100 ml flask equipped with magnetic stirring, thermometer and condenser, in an inert atmosphere (argon), at -10°C, anhydrous pyridine (py) (Merck) (1.1 ml) was added to a solution of 4,7-di-2-(N-2-ethylhexyl-5- formyldithienopyrrole)-5,6-di(2-octyldodecyloxy)benzothiadia zole (9) (247.6 mg; 0.18 mmol) obtained as described above, in anhydrous chloroform (CHCI3) (Merck) (55 ml): after removing the air from the reaction environment by means of 3 vacuum/argon cycles and placing the flask in a dry ice/ethanol bath, at -10°C, a solution, previously deaerated by 3 vacuum/argon cycles, of 5,6-difluoro-3- (dicyanomethylidene)indan-l-one (11) (Merck) (170 mg; 0.74 mmol) in anhydrous chloroform (Merck) (10 ml) was added, by dripping, in 15 minutes, to the reaction mixture. After removing the flask from the dry ice/ethanol bath and, again, removing the air from the reaction environment by means of 3 vacuum/argon cycles, the temperature was allowed to rise spontaneously to 20°C: after 10 minutes at 20°C, the reaction mixture was heated to 65°C and kept at said temperature, for 18 hours, under stirring. Subsequently, the temperature was allowed to drop spontaneously to 20°C and acetonitrile (Merck) (20 ml) was added: the reaction mixture was kept at said temperature, for 60 minutes, under stirring. Subsequently, most of the organic solvent was removed by distillation at reduced pressure and the remaining residue was taken up with chloroform (Merck) (10 ml): the solution obtained was added, by dripping, to acetonitrile (Merck) (20 ml). The obtained precipitate was isolated by filtration, washed with ethanol (Merck) (5 x 10 ml), acetonitrile (Merck) (1 x 10 ml) and finally with ethyl ether (Merck) (1 x 10 ml) obtaining 250 mg (0.14 mmol) of the compound GS017 (yield = 78%).

The compound GS017 was subjected to ^X H-NMR characterization as described above.

’H-NMR (400 MHz, Chloroform-^) 6 8.90 (s, 2H), 8.50 (m, 4H), 7.81 (s. br., 2H), 7.66 (t, J _H -F = 7.6Hz, 2H), 4.19 (m, 4H), 4.12 (d, J = 6.8Hz, 4H), 2.14 (m, 2H), 2.07 (m, 2H), 1.47 - 1.12 (m, 80H), 1.02 - 0.80 (m, 24H).

The compound GS017 was also subjected to the other characterizations indicated above: the absorption spectrum was acquired from which the optical energy gap (Eg ⁰ ) was determined and the values of the energy levels HOMO (EHOMO), LUMO (ELUMO) and electrochemical band-gap (E _gap Ec) were determined: the values obtained are reported in Table 2 and in Table 3.

Table 2 shows, in order: the compound, the solvent used, the value of the optical energy gap (Eg ⁰ ), expressed in (eV), the maximum value of the band at the lowest energy in the absorption spectrum [1 max (abs.)] expressed in (nm).

Table 3 shows, in order: the compound, the value of the HOMO energy level (EHOMO) expressed in (eV), the value of the LUMO energy level (ELUMO) expressed in (eV) and, finally the value of the electrochemical band-gap (E _gap Ec) expressed in (eV).

Figure 3 [the abscissa shows the potential (E) measured in volts (V) vs ferrocene/ferrocinium (Fc/Fc ⁺ ) and the ordinate shows the current density (i) measured in amperes (A)] shows the cyclic voltagram obtained by operating as described above.

EXAMPLE 3

Synthesis of compound GS028: 2.2A5.6-bis(2-octyldodccyloxy)bcnzo|c|| 1.2.5 |- thiadiazole-4,7-di-2-(N-2-ethylhexyldithienopyrrole)-6-diyl- bis-(methanyl- ylidene)-5,6-dichloro-3-oxo-2,3-dihvdro-lH-indene-2,l-diylid ene)dimalono- nitrile

Synthesis of the compound GS028

In a 100 ml flask equipped with magnetic stirring, thermometer and condenser, in an inert atmosphere (argon), at -10°C, anhydrous pyridine (py) (Merck) (1.1 ml) was added to a solution of 4,7-di-2-(A-2-ethylhexyl-5- formyldithienopyrrole)-5,6-di(2-octyl-dodecyloxy)benzothiadi azole (9) (247.6 mg; 0.18 mmol) obtained as described above, in anhydrous chloroform (CHCI3) (Merck) (55 ml): after having removed the air from the reaction environment by means of 3 vacuum/argon cycles, a solution, previously deaerated by 3 vacuum/argon cycles, of 5,6-dichloro-3-(dicyanomethylidene)indan-l-one (39) (Merck) (194.7 mg; 0.74 mmol) in anhydrous chloroform (Merck) (10 ml) was added, in 10 minutes by dripping. After removing the air from the reaction environment by means of 3 vacuum/argon cycles again, the temperature was allowed to rise spontaneously to 20°C: after 10 minutes at 20°C, the reaction mixture was heated to 65 °C and kept at said temperature, for 18 hours, under stirring. Subsequently, the temperature was allowed to drop spontaneously to 20°C and acetonitrile (Merck) (20 ml) was added: the reaction mixture was kept at said temperature, for 60 minutes, under stirring. Subsequently, most of the organic solvent was removed by distillation at reduced pressure and the remaining residue was taken up with chloroform (Merck) (10 ml): the solution obtained was added, by dripping, to acetonitrile (Merck) (20 ml). The obtained precipitate was isolated by filtration, washed with ethanol (Merck) (5 x 10 ml), acetonitrile (Merck) (l x 10 ml) and finally with ethyl ether (Merck) (1 x 10 ml) obtaining 222.2 mg (0.12 mmol) of the compound GS028 (yield = 67%).

The compound GS028 was subjected to ^X H-NMR characterization by operating as described above.

’H-NMR (400 MHz, Chloroform- d) 5 8.90 (s, 2H), 8.50 (m, 4H), 7.81 (s. br., 2H), 7.66 (t, JHF = 7.6Hz, 2H), 4.19 (m, 4H), 4.12 (d, J = 6.8Hz, 4H), 2.14 (m, 2H), 2.07 (m, 2H), 1.47 - 1.12 (m, 80H), 1.02 - 0.80 (m, 24H).

The compound GS028 was also subjected to the other characterizations indicated above: the absorption spectrum was acquired from which the optical energy gap (Eg ⁰ ) was determined and the values of the energy levels HOMO (EHOMO), LUMO (ELUMO) and electrochemical band-gap (E _gap Ec) were determined: the values obtained are reported in Table 2 and in Table 3.

Table 2 shows, in order: the compound, the solvent used, the value of the optical energy gap (Eg ⁰ ), expressed in (eV), the maximum value of the band at the lowest energy in the absorption spectrum [1 max (abs.)] expressed in (nm).

Table 3 shows, in order: the compound, the value of the HOMO energy level (EHOMO) expressed in (eV), the value of the LUMO energy level (ELUMO) expressed in (eV) and, finally the value of the electrochemical band-gap (E _gap Ec) expressed in (eV).

Figure 4 [the abscissa shows the potential (E) measured in volts (V) vs ferrocene/ferrocinium (Fc/Fc ⁺ ) and the ordinate shows the current density (i) measured in amperes (A)] shows the cyclic voltagram obtained by operating as described above.

EXAMPLE 4

Synthesis of compound GS018: 2,2'-(5,6-bis(3-(carbo-2-octyldecyloxy)- phenoxy)-benzo-[c][E2,51thiadiazole-47-di-2-(N-2-ethylhexyld ithienopyrrole)- 6-diyl-bis(methanylylidene)-5,6-difluoro-3-oxo-2,3-dihydro-l H-indene-2,l- diylidene)dimalononitrile

Synthesis of 2-octyldodecyl 3-hydroxybenzoate (14)

In a 100 ml flask equipped with magnetic stirring, thermometer and condenser, in an inert atmosphere (argon), the following were added: hydroxybenzoic acid (12) (Merck) (1.5 g; 10.86 mmol), (V,(V-di methyl formamide (DMF) anhydrous (Merck) (30 ml), 2-octyldodecylbromide (13) (Merck) (3.9 g; 10.86 mmol), potassium hydrogen carbonate (KHCO3) (Merck) (1.08 g; 10.86 mmoles) and potassium iodide (180.6 mg; 1.08 mmoles): the reaction mixture obtained was heated to 82°C and kept, under stirring, at said temperature, for 16 hours. Subsequently, the reaction mixture was poured into distilled water (50 ml) and, after adding a 1 M hydrochloric acid solution until pH 3 was reached, it was extracted with ethyl acetate (Merck) (3 x 30 ml). The organic phase (obtained by combining the three organic phases) was washed to neutral with distilled water (3 x 30 ml) and dried over sodium sulphate (Merck). The solvent was removed by distillation under reduced pressure and the residue obtained was purified by elution on a silica gel chromatographic column (eluent: n-heptane (Merck)/eluent 1 in a gradient from 95/5 to 90/10 to 80/20 v/v, in which the eluent 1 consists of a mixture of dichloromethane (Merck):ethyl acetate (Merck) in a ratio of 1:1 v/v), obtaining 4 g (9.6 mmol) of 2-octyldodecyl 3 -hydroxybenzoate (14) (yield = 89%).

Synthesis of 4,7-dibromo-5,6-di(2-carbo(2-octyldodecyloxy)phenoxy)benzoth ia- diazole (15)

In a 100 ml flask equipped with magnetic stirring, thermometer and condenser, under an inert atmosphere (argon), 2-octyldodecyl 3 -hydroxybenzoate (14) (2.5 g; 6.1 mmol) obtained as described above, and potassium carbonate (K2CO3) (Merck) (842 mg; 6.1 mmoles) were added to a solution of 4,7-dibromo- 5,6-difluorobenzothiadiazole (1) (Merck) (930 mg; 2.8 mmol) in anhydrous N,N- dimethylformamide (DMF) (Merck) (18 ml): the resulting mixture was heated to 82°C and kept at said temperature under stirring for 3 hours. Subsequently, the reaction mixture was poured into distilled water (50 ml) and extracted with ethyl ether (Merck) (3 x 30 ml). The organic phase (obtained by combining the three organic phases) was washed to neutral with distilled water (3 x 30 ml) and dried over sodium sulphate (Merck). The solvent was removed by distillation under reduced pressure and the residue obtained was purified by elution on a silica gel chromatographic column (eluent: n-heptane (Merck)/dichloromethane (Merck) in a gradient from 95/5 to 90/10 to 80/20 v/v) obtaining 2.8 g (2.5 mmoles) of 4,7- dibromo-5,6-di(3-carbo(2-octyldodecyloxy)phenoxy)benzothiadi azole (15) (yield = 88 %).

Synthesis of 4,7-di-2-(A-2-ethylhexyldithienopyrrole)-5,6-di(3-carbo(2-oc tyl- :yloxy)phenoxy)benzothiadiazole (16)

In a 100 ml flask equipped with magnetic stirring and thermometer, in an inert atmosphere (argon), 4,7-dibromo-5,6-di(3-carbo(2-octyldodecyloxy)- phenoxy)benzothiadiazole (15) (513 mg; 0.46 mmol) obtained as above described was added to a solution of A-2-ethylhexyl-2-tributylstannyldithienopyrrole (7) (1.16 mmol) obtained as described above, in anhydrous toluene (Merck) (15 ml). After removing the air present through 3 vacuum/nitrogen cycles, tris- dibenzylideneacetone dipalladium (Pd2dbas) (Merck) (10.5 mg; 0.011 mmol) and tris-o-tolylphosphine [P(o-tol)3] (Merck) (13.8 mg; 0.045 mmol) were added: after removing the air again by means of 3 vacuum/nitrogen cycles, the flask was immersed in an oil bath preheated to 110°C and the mixture obtained was kept, at said temperature, under stirring, for 12 hours. Subsequently, the reaction mixture was poured into distilled water (50 ml) and extracted with ethyl acetate (Merck) (3 x 50 mL). The organic phase (obtained by combining the three organic phases) was washed to neutral with distilled water (3 x 50 ml) and dried over sodium sulphate (Merck). After removing the solvent by distillation under reduced pressure, the residue obtained was purified by elution on a silica gel chromatographic column (eluent: n-heptane (Merck)/dichloromethane (Merck) in a gradient from 90/10 to 80/20 to 70/30 v/v), obtaining 478 mg (0.31 mmol) of 4,7-di-2-(A-2-ethylhexyldithienopyrrole)-5,6-di(3-carbo(2-oc tyldodecyloxy)- phenoxy)benzothiadiazole (16) (yield = 67%).

Synthesis of 4,7-di-2-(A-2-ethylhexyl-6-formyldithienopyrrole)-5,6-di(2-c arbo- (2-octyldodecyloxy)phenoxy)benzothiadiazole (17)

In a 100 ml flask equipped with magnetic stirring, thermometer and condenser, under an inert atmosphere (argon), at 0°C, A-di methyl formamide (DMF) (Merck) (0.958 ml) and, by dripping, phosphorus oxychloride (POCI3) (Merck) (0.798 ml; 1.31 g; 8.54 mmol) were added to a solution of 4,7-di-2-(A-2- ethylhexyldithienopyrrole)-5,6-di(3-carbo(2-octyldodecyloxy) phenoxy)benzo- thiadiazole (16) (478 mg; 0.31 mmol) obtained as described above, in anhydrous chloroform (CHCI3) (Merck) (12.3 ml): the reaction mixture was stirred and, after 30 minutes, was heated to 69°C and kept, under stirring, at said temperature, for 18 hours. Subsequently, the temperature was allowed to drop spontaneously to 20°C and a 10% aqueous solution of potassium acetate (20 ml) was added: the reaction mixture was kept, under stirring, at said temperature for 30 minutes and subsequently extracted with ethyl acetate (Merck) (3 x 30 ml). The organic phase (obtained by combining the three organic phases) was washed to neutral with distilled water (3 x 30 ml) and dried over sodium sulphate (Merck). After removing the solvent by distillation under reduced pressure, the residue obtained was purified by elution on a silica gel chromatographic column (eluent: n-heptane (Merck)/chloroform (Merck) in the ratio 1/1 v/v), obtaining 485 mg (0.31 mmol) of 4,7-di-2-(A-2-ethylhexyl-6-formyldithienopyrrole)-5,6-di(3-c arbo(2-octyl- dodecyloxy)phenoxy)benzothiadiazole (17) (99% yield).

Synthesis of the compound GS018

In a 100 ml flask equipped with magnetic stirring, thermometer and condenser, in an inert atmosphere (argon), at -10°C, anhydrous pyridine (py) (Merck) (1.8 ml) was added to a solution of 4,7-di-2-(A-2-ethylhexyl-6- formyldithienopyrrole)-5,6-di(3-carbo(2-octyldodecyloxy)phen oxy)benzothia- diazole (17) (485 mg; 0.31 mmol) obtained as described above, in anhydrous chloroform (CHCI3) (Merck) (80 ml): after having removed the air from the reaction environment, by means of 3 vacuum/argon cycles and having placed the flask in a bath of dry ice/ethanol, at -10°C, a solution, previously deaerated by 3 vacuum/argon cycles, of 5,6-difluoro-3-(dicyanomethylidene)indan-l-one (11) (Merck) (278.8 mg; 1.21 mmol) in anhydrous chloroform (Merck) (15 ml) was added to the reaction mixture, by dripping, in 15 minutes. After removing the flask from the dry ice/ethanol bath and, again, the air from the reaction environment by means of 3 vacuum/argon cycles, the temperature was allowed to rise spontaneously to 20°C: after 10 minutes at 20°C, the reaction mixture was heated to 65°C and kept at said temperature for 18 hours, under stirring. Subsequently, the temperature was allowed to drop spontaneously to 20°C and acetonitrile (Merck) (20 ml) was added: the reaction mixture was kept at said temperature, for 60 minutes, under stirring. Subsequently, most of the organic solvent was removed by distillation at reduced pressure and the remaining residue was taken up with chloroform (Merck) (10 ml): the solution obtained was added, by dripping, to acetonitrile (Merck) (20 ml). The obtained precipitate was isolated by filtration, washed with ethanol (Merck) (5 x 10 ml), acetonitrile (Merck) (1 x 10 ml) and finally with ethyl ether (Merck) (1 x 10 ml) obtaining 500 mg (0.25 mmol) of the compound GS018 (yield = 80%).

The compound GS018 was subjected to ^X H-NMR characterization by operating as described above.

’H-NMR (400 MHz, Chloroform- d) 5 8.79 (s, 2H), 8.65 (s, 2H), 8.46 (dd, JHF = 9.9, 6.4 Hz, 2H), 7.82 (dt, J = 7.8, 1.3 Hz, 2H), 7.74 (s. br., 2H), 7.62 (t, JHF = 7.7 Hz, 2H), 7.44 (t, J = 8.1 Hz, 2H), 7.41 (dd, J = 2.8, 1.5 Hz, 2H), 7.00 (m, 2H), 4.16 (d, J= 5.5Hz, 4H), 4.09 (m, 4H), 1.93 (m, 2H), 1.71 (m, 2H), 1.43 - 1.12 (m, 80H), 0.98 - 0.77 (m, 24H).

The compound GS018 was also subjected to the other characterizations indicated above: the absorption spectrum was acquired from which the optical energy gap (Eg ⁰ ) was determined and the values of the energy levels HOMO (EHOMO), LUMO (ELUMO) and electrochemical band-gap (E _gap Ec) were determined: the values obtained are reported in Table 2 and in Table 3.

Table 2 shows, in order: the compound, the solvent used, the value of the optical energy gap (Eg ⁰ ), expressed in (eV), the maximum value of the band at the lowest energy in the absorption spectrum [1 max (abs.)] expressed in (nm).

Table 3 shows, in order: the compound, the value of the HOMO energy level (EHOMO) expressed in (eV), the value of the LUMO energy level (ELUMO) expressed in (eV) and, finally the value of the electrochemical band-gap (E _gap Ec) expressed in (eV).

Figure 5 [the abscissa shows the potential (E) measured in volts (V) vs ferrocene/ferrocinium (Fc/Fc ⁺ ) and the ordinate shows the current density (i) measured in amperes (A)] shows the cyclic voltagram obtained by operating as described above.

EXAMPLE 5

Synthesis of compound GS019: 2,2'-(5,6-bis(4-(carbo-2-octyldodecyloxy)- phenoxy)benzo[c][l,2,5]thiadiazole-4,7-di-2-(N-2-ethylhexyld ithienopyrrole)-6- diyl-bis(methanylylidene)-5,6-difluoro-3-oxo-2,3-dihydro-lH- indene-2,l- diylidenejdimalononitrile

Synthesis of 2-octyldodecyl 4-hydroxybenzoate (19)

Into a 50 ml, microwave safe, vial, the following were added: 4- hydroxybenzoic acid (18) (Merck) (1.5 g; 10.86 mmol), (V,(V-di methyl formamide (DMF) anhydrous (Merck) (30 ml), 2-octyldodecylbromide (13) (Merck) (3.9 g; 10.86 mmol), potassium hydrogen carbonate (KHCO3) (Merck) (1.08 g; 10.86 mmol) and potassium iodide (KI) (Merck) (180.6 mg; 1.08 mmol): after insufflation with argon, the vial was microwaved (Discover SP-D - CEM Corp.). After 1 hour, at 80°C, under stirring (medium stirring), the reaction mixture was poured into distilled water (50 ml) and extracted with ethyl ether (Merck) (3 x 30 ml). The organic phase (obtained by combining the three organic phases) was washed to neutral with distilled water (3 x 20 ml) and dried over sodium sulphate (Merck). The solvent was removed by distillation under reduced pressure and the residue obtained was purified by elution on a silica gel chromatographic column (eluent: n-heptane (Merck)/eluent 1 in a gradient from 95/5 to 90/10 to 80 /20 v/v, in which the eluent 1 consists of a mixture of dichloromethane (Merck) :ethyl acetate (Merck) in a ratio of 1:1 v/v), obtaining 3 g (7.17 mmol) of 2-octyldodecyl

4-hydroxybenzoate (19) (yield = 70%).

Synthesis of 4,7-dibromo-5,6-di(4-carbo(2-< diazole

In a 100 ml flask equipped with magnetic stirring, thermometer and condenser, under an inert atmosphere (argon), 2-octyldodecyl 4-hydroxybenzoate (19) (2.17 g; 5.2 mmol) obtained as described above, and potassium carbonate (K2CO3) (Merck) (717 mg; 5.2 mmoles) were added to a solution of 4,7-dibromo- 5,6-difluorobenzothiadiazole (1) (Merck) (800 mg; 2.4 mmol) in anhydrous N,N- dimethylformamide (DMF) (Merck) (15 ml): the reaction mixture obtained was heated to 82°C and kept at said temperature under stirring, for 12 hours. Subsequently, the reaction mixture was poured into distilled water (50 ml) and extracted with ethyl ether (Merck) (3 x 30 ml). The organic phase (obtained by combining the three organic phases) was washed to neutral with distilled water (3 x 30 ml) and dried over sodium sulphate (Merck). The solvent was removed by distillation under reduced pressure and the residue obtained was purified by elution on a silica gel chromatographic column (eluent: n-heptane (Merck)/dichloromethane (Merck) in a gradient from 95/5 to 90/10 to 80/20 v/v) obtaining 2.6 g (2.3 mmoles) of 4,7-dibromo-5,6-di(4-carbo(2-octyldodecyloxy)- phenoxy)benzo thiadiazole (20) (yield = 88 %).

Synthesis of 4,7-di-2-(A-2-ethylhexyldithienonyrrole)-5,6-di(4-carbo(2-oc tyl-

(21)

In a 100 ml flask equipped with magnetic stirring and thermometer, in an inert atmosphere (argon), 4,7-dibromo-5,6-di(4-carbo(2-octyldodecyloxy)- phenoxy)benzothiadiazole (20) (513 mg; 0.46 mmol) obtained as described above was added to a solution of A-2-ethylhexyl-2-tributylstannyldithienopyrrole (7) (1.16 mmol) obtained as described above, in anhydrous toluene (Merck) (15 ml). After removing the air present through 3 vacuum/nitrogen cycles, tris- dibenzylideneacetone dipalladium (Pd2dbas) (Merck) (10.5 mg; 0.011 mmol) and tris-o-tolylphosphine [P(o-tol)3] (Merck) (13.8 mg; 0.045 mmol) were added: after having again removed the air present by means of 3 vacuum/nitrogen cycles, the flask was placed in an oil bath preheated to 110°C and the reaction mixture obtained was kept, at said temperature, under stirring, for 12 hours. Subsequently, the reaction mixture was poured into distilled water (50 ml) and extracted with ethyl acetate (Merck) (3 x 50 ml). The organic phase (obtained by combining the three organic phases) was washed to neutral with distilled water (3 x 50 ml) and dried over sodium sulphate (Merck). After removing the solvent by distillation under reduced pressure, the residue obtained was purified by elution on a silica gel chromatographic column (eluent: n-heptane (Merck)/dichloromethane (Merck) in a gradient of 9/1 to 8/2 at 7/3 to 6/4 at 1/1 v/v), obtaining 500 mg (0.26 mmol) of 4,7-di-2-(A-2-ethylhexyldithienopyrrole)-5,6-di(4-carbo(2-oc tyl- dodecyloxy)phenoxy)benzothiadiazole (21) (yield = 70%).

Synthesis of 4,7-di-2-(A-2-ethylhexyl-6-formyldithienopyrrole)-5,6-di(4-c arbo- (2-octyldodecyloxy)phenoxy)benzothiadiazole (22)

In a 100 ml flask equipped with magnetic stirring, thermometer and condenser, under an inert atmosphere (argon), at 0°C, A-di methyl formamide (DMF) (Merck) (0.8 ml) and, by dripping, phosphorus oxychloride (POCI3) (Merck) (0.646 ml; 1.06 g; 6.9 mmol) were added, to a solution of 4,7-di-2-(A-2- ethylhexyldithienopyrrole)-5,6-di(4-carbo(2-octyldodecyloxy) phenoxy)benzo- thiadiazole (21) (380 mg; 0.25 mmol) obtained as described above, in anhydrous chloroform (CHCI3) (Merck) (10 ml): the reaction mixture was stirred and, after 30 minutes, was heated to 69°C and kept, under stirring, at said temperature, for 48 hours. Subsequently, the temperature was allowed to drop spontaneously to 20°C and a 10% aqueous solution of potassium acetate (20 ml) was added: the reaction mixture was kept, under stirring, at said temperature for 30 minutes, and subsequently extracted with ethyl acetate (Merck) (3 x 30 ml). The organic phase (obtained by combining the three organic phases) was washed to neutral with distilled water (3 x 30 ml) and dried over sodium sulphate (Merck). After removing the solvent by distillation under reduced pressure, the residue obtained was purified by elution on a silica gel chromatographic column (eluent: n-heptane (Merck)/chloroform (Merck) in a gradient from 6/4 to 1/ 1 to 4/6 v/v), obtaining 345.3 mg (0.22 mmol) of 4,7-di-2-(A-2-ethylhexyl-6-formyldithienopyrrole)-5,6- di(4-carbo(2-octyldodecyloxy)phenoxy)-benzothiadiazole (22) (83.3% yield).

Synthesis of the compound GS019

In a 100 ml flask equipped with magnetic stirring, thermometer and condenser, in an inert atmosphere (argon), at -10°C, anhydrous pyridine (py) (Merck) (1.3 ml) was added to a solution of 4,7-di-2-(A-2-ethylhexyl-6- formyldithienopyrrole)-5,6-di(4-carbo(2-octyldodecyloxy)phen oxy)benzo- thiadiazole (22) (345.3 mg; 0.22 mmol) obtained as described above, in anhydrous chloroform (CHCh) (Merck) (63 ml): after removing the air from the reaction environment, by means of 3 vacuum/argon cycles and placing the flask in a dry ice/ethanol bath, at -10°C, a solution of 5,6-difluoro-3- (dicyanomethylidene)indan-l-one (11) (Merck) (198 mg; 0.86 mmol) in anhydrous chloroform (Merck) (12 ml), was added, by dripping, in 15 minutes, to the reaction mixture. After removing the flask from the dry ice/ethanol bath and, again, the air from the reaction environment by means of 3 vacuum/argon cycles, the temperature was allowed to rise spontaneously to 20°C: after 10 minutes at 20°C, the reaction mixture was heated to 65°C and kept at said temperature for 18 hours, under stirring. Subsequently, the temperature was allowed to drop spontaneously to 20°C and acetonitrile (Merck) (20 ml) was added: the reaction mixture was kept at said temperature, for 60 minutes, under stirring. Subsequently, most of the organic solvent was removed by distillation at reduced pressure and the remaining residue was taken up with chloroform (Merck) (10 ml): the solution obtained was added, by dripping, to acetonitrile (Merck) (20 ml). The obtained precipitate was isolated by filtration, washed with ethanol (Merck) (5 x 10 ml), acetonitrile (Merck) (1 x 10 ml) and finally with ethyl ether (Merck) (1 x 10 ml) obtaining 368 mg (0.18 mmol) of the compound GS019 (yield = 82%). The compound GS019 was subjected to ^X H-NMR characterization by operating as described above.

¹ H-NMR (400 MHz, Chloroform- d) 5 8.82 (s, 2H), 8.60 (s, 2H), 8.48 (dd, JHF= 10.0, 6.5 Hz, 2H), 8.05 (m, 4H), 7.75 (s. br., 2H), 7.64 (t, JHF 7 = 7.6HZ, 2H), 6.86 (m, 4H), 4.22 (d, J = 5.6Hz, 4H), 4.11 (m, 4H), 1.94 (m, 2H), 1.75 (m, 2H), 1.46 - 1.13 (m, 80H), 0.97 - 0.77 (m, 24H).

The compound GS019 was also subjected to the other characterizations indicated above: the absorption spectrum was acquired from which the optical energy gap (Eg ⁰ ) was determined and the values of the energy levels HOMO (EHOMO), LUMO (ELUMO) and electrochemical band-gap (E _gap Ec) were determined: the values obtained are reported in Table 2 and in Table 3.

Table 2 shows, in order: the compound, the solvent used, the value of the optical energy gap (Eg ⁰ ), expressed in (eV), the maximum value of the band at the lowest energy in the absorption spectrum [1 max (abs.)] expressed in (nm).

Table 3 shows, in order: the compound, the value of the HOMO energy level (EHOMO) expressed in (eV), the value of the LUMO energy level (ELUMO) expressed in (eV) and, finally the value of the electrochemical band-gap (E _gap Ec) expressed in (eV).

Figure 6 [the abscissa shows the potential (E) measured in volts (V) vs ferrocene/ferrocinium (Fc/Fc ⁺ ) and the ordinate shows the current density (i) measured in amperes (A)] shows the cyclic voltagram obtained by operating as described above.

EXAMPLE 6

Synthesis of the compound GS020: 2,2'-(5,6-bis(2-(carbo-2-octyldodecyloxy)- phenoxy)benzo[c][l,2,5]thiadiazole-4,7-di-2-(N-2-ethylhexyld ithienopyrrole)-6- diyl-bis(methanylylidene)-5,6-difluoro-3-oxo-2,3-dihydro-lH- indene-2,l- diylidenejdimalononitrile

Synthesis of 2-octyldodecyl 2-hydroxybenzoate (24)

In a 100 ml flask equipped with magnetic stirring, thermometer and condenser, in an inert atmosphere (argon), the following were added: salicylic acid (23) (Merck) (1.5 g; 10.86 mmoles), (V,(V-di methyl formamide (DMF) anhydrous

(Merck) (30 ml), 2-octyldodecylbromide (13) (Merck) (3.9 g; 10.86 mmol), potassium hydrogen carbonate (KHCO3) (Merck) (1.08 g ; 10.86 mmol) and potassium iodide (KI) (Merck) (180.6 mg; 1.08 mmol): the reaction mixture was heated to 82°C and kept, at said temperature, under stirring, for 16 hours. Subsequently, the reaction mixture was poured into distilled water (50 ml) and after adding a 1 M hydrochloric acid solution (Merck) until pH 3 was reached, it was extracted with ethyl ether (Merck) (3 x 30 ml). The organic phase (obtained by combining the three organic phases) was washed to neutral with distilled water (3 x 20 ml) and dried over sodium sulphate (Merck). The solvent was removed by distillation under reduced pressure and the residue obtained was purified by elution on a silica gel chromatographic column (eluent: n-heptane (Merck)/eluent 1 in a gradient from 95/5 to 90/10 to 80 /20 v/v, in which the eluent 1 consists of a mixture of dichloromethane (Merck):ethyl acetate (Merck) in a ratio of 1: 1 v/v), obtaining 4 g (9.6 mmol) of 2-octyldodecyl 2-hydroxybenzoate (24) (yield = 89%).

Synthesis of 4,7-dibromo-5,6-di(2-carbo(2-octyldodecyloxy)phenoxy)benzoth ia- diazole (25)

In a 100 ml flask equipped with magnetic stirring, thermometer and condenser, under an inert atmosphere (argon), 2-octyldodecyl 2-hydroxybenzoate (24) (2.5 g; 6.1 mmol) obtained as described above, and potassium carbonate (K2CO3) (Merck) (842 mg; 6.1 mmol) were added to a solution of 4,7-dibromo- 5,6-difluorobenzothiadiazole (1) (Merck) (930.3 mg; 2.8 mmol) in anhydrous A/.A i methyl formamide (DMF) (Merck) (18 ml): the reaction mixture obtained was heated to 82°C and kept at said temperature under stirring, for 12 hours. Subsequently, the reaction mixture was poured into distilled water (50 ml) and extracted with ethyl ether (Merck) (3 x 30 ml). The organic phase (obtained by combining the three organic phases) was washed to neutral with distilled water (3 x 30 ml) and dried over sodium sulphate (Merck). The solvent was removed by distillation under reduced pressure and the residue obtained was purified by elution on a silica gel chromatographic column (eluent: n-heptane (Merck)/dichloromethane (Merck) in a gradient from 95/5 to 90/10 to 80/20 v/v) obtaining 3.04 g (2.7 mmoles) of 4,7-dibromo-5,6-di(2-carbo(2-octyl- dodecyloxy)phenoxy)benzothiadiazole (25) (yield = 96 %).

Synthesis of 4,7-di-2-(A^-2-ethylhexyldithienopyrrole)-5,6-di(2-carbo(2- octyldodecyl-oxy)phenoxy)benzothiadiazole (26)

In a 100 ml flask equipped with magnetic stirring and thermometer, in an inert atmosphere (argon), 4,7-dibromo-5,6-di(2-carbo(2- octyldodecyloxy)phenoxy)benzothiadiazole (25) (1.04 g; 0.92 mmol) obtained as described above, was added to a solution of A-2-ethylhexyl-2- tributylstannyldithienopyrrole (7) (2.5 mmol) obtained as described above, in anhydrous toluene (Merck) (20 ml). After removing the air present through 3 vacuum/nitrogen cycles, tris-dibenzylideneacetone dipalladium (Pd2dbas) (Merck) (21 mg; 0.023 mmol) and tris-o-tolylphosphine [P(o-tol)3] (Merck) (27.8 mg; 0.09 mmol) were added: after having again removed the air present by means of 3 vacuum/nitrogen cycles, the flask was placed in an oil bath preheated to 110°C and the reaction mixture obtained was kept, at said temperature, under stirring, for 12 hours. Subsequently, the reaction mixture was poured into distilled water (50 ml) and extracted with ethyl acetate (Merck) (3 x 50 mL). The organic phase (obtained by combining the three organic phases) was washed to neutral with distilled water (3 x 50 ml) and dried over sodium sulphate (Merck). After removing the solvent by distillation under reduced pressure, the residue obtained was purified by elution on a silica gel chromatographic column (eluent: n-heptane (Merck)/dichloromethane (Merck) in a gradient of 9/1 to 8/2 at 7/3 v/v), obtaining 1.25 g (0.81 mmol) of 4,7-di-2-(A-2-ethylhexyldithienopyrrole)-5,6-di(2-carbo(2- octyldodecyloxy)phenoxy)benzothiadiazole (26) (yield = 88%).

Synthesis of 4,7-di-2-(A-2-ethylhexyl-6-formyldithienopyrrole)-5,6-di(2- carbo(2-octyldodecyloxy)phenoxy)benzothiadiazole (27)

In a 100 ml flask equipped with magnetic stirring, thermometer and condenser, under an inert atmosphere (argon), at 0°C, A-di methyl formamide (DMF) (Merck) (1.05 ml) and, by dripping, phosphorus oxychloride (POCI3) (Merck) (0.854 ml; 1.4 g; 9.13 mmol) were added to a solution of 4,7-di-2-(A-2- ethylhexyldithienopyrrole)-5,6-di(2-carbo(2-octyldodecyloxy) phenoxy)benzo- thiadiazole (26) (512 mg; 0.33 mmol) obtained as described above, in anhydrous chloroform (CHCI3) (Merck) (13.2 ml): the mixture reaction was stirred and, after 30 minutes, was heated to 69°C and kept, under stirring, at said temperature for 18 hours. Subsequently, the temperature was allowed to drop spontaneously to 20°C and a 10% aqueous solution of potassium acetate (20 ml) was added: the reaction mixture was kept, under stirring, at said temperature for 30 minutes and subsequently extracted with ethyl acetate (Merck) (3 x 30 ml). The organic phase (obtained by combining the three organic phases) was washed to neutral with distilled water (3 x 30 ml) and dried over sodium sulphate (Merck). After removing the solvent by distillation under reduced pressure, the residue obtained was purified by elution on a silica gel chromatographic column (eluent: n-heptane (Merck)/chloroform (Merck) in a gradient of 6/4 to 1/1 v/v), obtaining 488.7 mg (0.3 mmol) of 4,7-di-2-(A-2-ethylhexyl-6-formyldithienopyrrole)-5,6-di(2- carbo(2-octyldodecyloxy)phenoxy)benzothiadiazole (27) (92% yield).

Synthesis of the GS020 compound

In a 100 ml flask equipped with magnetic stirring, thermometer and condenser, in an inert atmosphere (argon), at -10°C, anhydrous pyridine (py) (Merck) (1.83 ml) was added to a solution of 4,7-di-2-(A-2-ethylhexyl-6- formyldithienopyrrole)-5,6-di(2-carbo(2-octyldodecyloxy)phen oxy)-benzo- thiadiazole (27) (488.7 mg; 0.305 mmol) obtained as described above, in anhydrous chloroform (CHCI3) (Merck) (80 ml): after removing the air from the reaction environment, by means of 3 vacuum/argon cycles and placing the flask in a dry ice/ethanol bath, at -10°C, a solution previously deaerated by 3 vacuum/argon cycles, of 5,6-difluoro-3-(dicyanomethylidene)indan-l-one (11) (Merck) (280 mg; 1.22 mmol) in anhydrous chloroform (Merck) (20 ml) was added, by dripping, in 15 minutes, to the reaction mixture. After removing the flask from the dry ice/ethanol bath and, again, the air from the reaction environment by means of 3 vacuum/argon cycles, the temperature was allowed to rise spontaneously to 20°C: after 10 minutes at 20°C, the reaction mixture was heated to 65°C and kept at said temperature for 18 hours, under stirring. Subsequently, the temperature was allowed to drop spontaneously to 20°C and acetonitrile (Merck) (20 ml) was added: the reaction mixture was kept at said temperature, for 60 minutes, under stirring. Subsequently, most of the organic solvent was removed by distillation at reduced pressure and the remaining residue was taken up with chloroform (Merck) (10 ml): the solution obtained was added, by dripping, to acetonitrile (Merck) (20 ml). The obtained precipitate was isolated by filtration, washed with ethanol (Merck) (5 x 10 ml), acetonitrile (Merck) (l x 10 ml) and finally with ethyl ether (Merck) (1 x 10 ml) obtaining 500 mg (0.25 mmol) of the compound GS020 (yield = 82%).

The compound GS020 was subjected to ^X H-NMR characterization by operating as described above.

’H-NMR (400 MHz, Chloroform-^) 6 8.77 (s, 2H), 8.71 (s, 1H), 8.68 (s, 1H), 8.46 (m, 2H), 7.88 (d, J = 7.8 Hz, 2H), 7.71 (s. br., 2H), 7.61 (t, J HF = 7.6 Hz, 2H), 7.41 (m, 2H), 7.14 (s, 2H), 6.89 (s, 2H), 4.07 (m, 4H), 3.89 (m, 4H), 1.88 (m, 2H), 1, 68 (m, 2H), 1.46 - 1.00 (m, 80H), 0.98 - 0.67 (m, 24H).

The compound GS020 was also subjected to the other characterizations indicated above: the absorption spectrum was acquired from which the optical energy gap (Eg ⁰ ) was determined and the values of the energy levels HOMO (EHOMO), LUMO (ELUMO) and electrochemical band-gap (E _gap Ec) were determined: the values obtained are reported in Table 2 and in Table 3.

Table 2 shows, in order: the compound, the solvent used, the value of the optical energy gap (Eg ⁰ ), expressed in (eV), the maximum value of the band at the lowest energy in the absorption spectrum [1 max (abs.)] expressed in (nm).

Table 3 shows, in order: the compound, the value of the HOMO energy level (EHOMO) expressed in (eV), the value of the LUMO energy level (ELUMO) expressed in (eV) and, finally the value of the electrochemical band-gap (E _gap Ec) expressed in (eV).

Figure 7 [the abscissa shows the potential (E) measured in volts (V) vs ferrocene/ferrocinium (Fc/Fc ⁺ ) and the ordinate shows the current density (i) measured in amperes (A)] shows the cyclic voltagram obtained by operating as described above.

EXAMPLE 7

Synthesis of compound GS022: 2,2'-(5,6-di(2-butyloctyloxy)benzo[c][l,2,5]- thiadiazole-4,7-di-2-(N-undecyldithyenopyrrole)-6-diyl-bis(m ethanylylidene)- 5,6-difluoro-3-oxo-2,3-dihydro-lH-indene-2,l-diylidene)dimal ononitrile

Synthesis of 4,7-dibromo-5,6-di(2-butyloctyloxy)benzothiadiazole (36)

In a 100 ml flask equipped with magnetic stirring, thermometer and condenser, sodium hydride (NaH) (60% dispersion in mineral oil) (Merck) (188 mg; 4.7 mmoles) was added in a single portion to a solution of 2-butyloctanol (35) (Merck) (964.2 mg; 5.24 mmol) in anhydrous tetrahydrofuran (Merck) (20 ml): the reaction mixture obtained was heated to 50°C and kept, under stirring, at said temperature for 3 hours. Subsequently, a solution of 4,7-dibromo-5,6- difluorobenzothiadiazole (1) (Merck) (700 mg; 2.12 mmol) in anhydrous tetrahydrofuran (THF) (Merck) (10 ml) was added by dripping : the reaction mixture obtained was kept at 50°C, under stirring, for 18 hours. Subsequently, the reaction mixture was poured into distilled water (50 ml) and extracted with ethyl ether (Merck) (3 x 30 ml). The organic phase (obtained by combining the three organic phases) was washed to neutral with distilled water (3 x 30 ml) and dried over sodium sulphate (Merck). The solvent was removed by distillation under reduced pressure and the residue obtained was purified by elution on a silica gel chromatographic column (eluent: n-heptane (Merck)/dichloromethane (Merck) in a gradient from 95/5 to 90/10 to 85/15 v/v) obtaining 1.15 g (1.75 mmoles) of 4,7- dibromo-5,6-di(2-butyloctyloxy)benzothiadiazole (36) (yield = 82.5%).

Synthesis of 4,7-di-2-(A-undecyldithyenopyrrole)-5,6-di(2-butyloctyloxy)b enzo- thiadiazole (37)

In a 100 ml flask equipped with magnetic stirring, thermometer and condenser, in an inert atmosphere (argon), 4,7-dibromo-5,6-di(2- butyloctyloxy)benzothiadiazole (36) (353.7 mg; 0.54 mmol) obtained as described above was added to a solution of A-(undecyl)-2-tributylstanylthienothiophene (32) (1.29 mmol) obtained as described above, in anhydrous toluene (Merck) (15 ml). After removing the air present through 3 vacuum/nitrogen cycles, tris- dibenzylideneacetone dipalladium (Pd2dbas) (Merck) (14.6 mg; 0.016 mmol) and tris-o-tolylphosphine [P(o-tol)3] (Merck) (19.6 mg; 0.064 mmol) were added: after having again removed the air present by means of 3 vacuum/nitrogen cycles, the flask was immersed in an oil bath preheated to 110°C and the reaction mixture obtained was kept, at said temperature, under stirring, for 12 hours. Subsequently, the reaction mixture was poured into distilled water (50 ml) and extracted with ethyl acetate (Merck) (3 x 50 mL). The organic phase (obtained by combining the three organic phases) was washed to neutral with distilled water (3 x 50 ml) and dried over sodium sulphate (Merck). After removing the solvent by distillation under reduced pressure, the residue obtained was purified by elution on a silica gel chromatographic column (eluent: n-heptane (Merck)/dichloromethane (Merck) in a gradient of 95/5 to 90/10 v/v), obtaining 442 mg (0.38 mmol) of 4,7- di-2-(A-undecylthyenopyrrole)-5,6-di(2-butyloctyloxy)benzoth iadiazole (37) (yield = 67%).

Synthesis of 4,7-di-2-(A-undecyl-6-formyldithienopyrrole)-5,6-di(2-butyl- octyloxy)benzothiadiazole (38)

In a 100 ml flask equipped with magnetic stirring, thermometer and condenser, under an inert atmosphere (argon), at 0°C, A-di methyl formamide (DMF) (Merck) (1.2 ml) and, by dripping, phosphorus oxychloride (POCI3) (Merck) (0.97 ml; 1.6 g; 10.4 mmol) were added to a solution of 4,7-di-2-(/V- undecyldithienopyrrole)-5,6-di (2-butyloctyloxy)benzothiadiazole (37) (442 mg; 0.38 mmol) obtained as described above, in anhydrous chloroform (CHCI3) (Merck) (15 ml): the reaction mixture was placed under stirring and, after 30 minutes, was heated to 69°C and kept, under stirring, at said temperature, for 18 hours. Subsequently, the temperature was allowed to drop spontaneously to 20°C and a 10% aqueous solution of potassium acetate (20 ml) was added: the reaction mixture was kept, under stirring, at said temperature for 30 minutes and subsequently extracted with ethyl acetate (Merck) (3 x 30 ml). The organic phase (obtained by combining the three organic phases) was washed to neutral with distilled water (3 x 30 ml) and dried over sodium sulphate (Merck). After removing the solvent by distillation under reduced pressure, the obtained residue was purified by elution on silica gel column chromatography (eluent: n-heptane (Merck)/chloroform (Merck) 1/1 v/v), obtaining 450 mg (0.37 mmol) of 4,7-di-2- (A-undecyl-6-formyldithienopyrrole)-5,6-di(2-butyloctyloxy)b enzothiadiazole (38) (97% yield).

Synthesis of the compound GS022

In a 100 ml flask equipped with magnetic stirring, thermometer and condenser, in an inert atmosphere (argon), at -10°C, anhydrous pyridine (py) (Merck) (1.25 ml) was added to a solution of 4,7-di-2-(A-undecyl-6- formyldithienopyrrole)-5,6-di(2-butyloctyloxy)benzothiadiazo le (38) (260.7 mg; 0.21 mmol) obtained as described above, in anhydrous chloroform (CHCI3) (Merck) (60 ml): after having removed the air from the reaction environment by means of 3 vacuum/argon cycles and having placed the flask in a bath of dry ice/ethanol, at -10°C, a solution, previously deaerated by 3 vacuum/argon cycles, of 5,6-difluoro-3-(dicyanomethylidene)indan-l-one (11) (Merck) (193.5 mg; 0.84 mmol) in chloroform anhydrous (Merck) (10 ml) was added, by dripping, in 15 minutes, to the reaction mixture. After removing the flask from the dry ice/ethanol bath and, again, the air from the reaction environment by means of 3 vacuum/argon cycles, the temperature was allowed to rise spontaneously to 20°C: after 10 minutes at 20°C, the reaction mixture was heated to 65°C and kept at said temperature for 18 hours, under stirring. Subsequently, the temperature was allowed to fall spontaneously to 20°C and acetonitrile (Merck) (20 ml) was added: the reaction mixture was kept at said temperature, for 60 minutes, under stirring. Subsequently, most of the organic solvent was removed by distillation at reduced pressure and the remaining residue was taken up with chloroform (Merck) (10 ml): the solution obtained was added, by dripping, to acetonitrile (Merck) (20 ml). The obtained precipitate was isolated by filtration, washed with ethanol (Merck) (5 x 10 ml), acetonitrile (Merck) (1 x 10 ml) and finally with ethyl ether (Merck) (l x 10 ml) obtaining 335 mg (0.20 mmol) of the compound GS022 (yield = 97%).

The compound GS022 was subjected to ’H-NMR characterization by operating as described above.

’H-NMR. (400 MHz, Chloroform- d) 8 8.86 (s, 2H), 8.54 - 8.39 (m, 4H), 7.78 (s. br., 2H), 7.65 (t, J H-F= 7.5 Hz, 2H), 4.32 (t, 7.1 Hz, 4H), 4.13 (d, J =

6.9 Hz, 4H), 1.97 (m, 6H), 1.48 - 1.14 (m, 52H), 0.96 - 0.78 (m, 18H)

The compound GS022 was also subjected to the other characterizations indicated above: the absorption spectrum was acquired from which the optical energy gap (Eg ⁰ ) was determined and the values of the energy levels HOMO (EHOMO), LUMO (ELUMO) and electrochemical band-gap (E _gap Ec) were determined: the values obtained are reported in Table 2 and in Table 3.

Table 2 shows, in order: the compound, the solvent used, the value of the optical energy gap (Eg ⁰ ), expressed in (eV), the maximum value of the band at the lowest energy in the absorption spectrum [1 max(abs )] expressed in (nm).

Table 3 shows, in order: the compound, the value of the HOMO energy level (EHOMO) expressed in (eV), the value of the LUMO energy level (ELUMO) expressed in (eV) and, finally the value of the electrochemical band-gap (E _gap Ec) expressed in (eV).

Figure 8 [the abscissa shows the potential (E) measured in volts (V) vs ferrocene/ferrocinium (Fc/Fc ⁺ ) and the ordinate shows the current density (i) measured in amperes (A)] shows the cyclic voltagram obtained by operating as described above.

RECTIFIED SHEET (RULE 91) ISA/EP Table 2

Table 3