FIELD OF INVENTION

[0001] This invention relates to polymer charge-storage systems, and particularly to new materials for thin-film charge-storage devices, such as battery/supercapacitor hybrids, which enable the reduction in thickness of the charge-storage device and an increase in energy density. The invention also relates to a method of manufacturing these devices. BACKGROUND OF THE INVENTION

[0002] In the recent years, there has been increasing interest in the development of thin film charge-storage devices which exhibit both excellent energy and power density.

[0003] Thin film batteries generally achieve high energy densities but typically provide low power due reversible coulombic reactions occurring at the electrodes, involving charge transfer and ion diffusion in electrode materials, thereby kinetically limiting the power delivery as well as the recharging time. On the other hand, supercapacitors store energy through accumulation of ions on the electrode surface, i.e. through a coulombic charge storage process, so that supercapacitors may provide more power per unit mass than batteries and enable burst power supply for electric vehicles, for example.

[0004] Thin film charge-storage devices comprising n- and p-type electroactive conjugated polymers have previously been demonstrated to offer good conductivity of both ions and charges that allow them to act as redox-active materials in charge-storage devices {see e.g. US 4,442,187 A). In these, they show properties of both batteries and supercapacitors, depending on a number of factors including the degree of shielding of each charge from the next one along the polymer chain, and the relative mobility of charges and ions within the polymer layers.

[0005] Conventional polymer battery-supercapacitor hybrid technologies often use materials that were often developed for other purposes. These materials are mostly non- ionic in basis and therefore limit the types of device, and the methods of operation that can be used, which may be exemplified by means of the typical configuration of a thin film charge-storage device and its functioning as illustrated in Figures 1 A and 1 B. Herein, the electron flow and ion movement during charge (Fig. 1A) and discharge (Fig. 1 B) are shown. During charging, an n-type polymer in the electroactive polymer layer (2) at the cathode side (1 ) becomes negatively charged and cations from the electrolyte move in from the separator (3) to compensate the charge. Simultaneously, the p-type polymer in the electroactive polymer layer (4) at the anode side (5) becomes positively charged, and anions from the electrolyte move in to compensate the charge. During discharge, both polymers return to their neutral states, and ions return to the solution. A characteristic feature of such a device is that two different ions are required, which both typically originate in a liquid form inside the separating membrane between the two electroactive polymer materials and frequently take the form of an ionic liquid. Accordingly, such a configuration requires the separator layer to store all ionic species in the discharged state. However, as a result, the separator must have a sufficient thickness to satisfactorily perform as an ion reservoir (typically about one third or more of the overall thickness of the electroactive layers), which imposes limitations on the dimensions of the overall charge storage device, the current output, and also the internal resistance.

[0006] From the technical field of ion-conductive materials and polymer electrolytes, it is known to modify oligomers or polymers with acidic substituent groups in order to enhance their ion conductivity (see e.g. US 2013/0216936 A1 or US 2008/0045615 A1). However, the abovementioned problems have hitherto not been addressed.

[0007] Therefore, it is still desirable to provide a thin film charge-storage device, wherein the separator can be reduced to a minimal thickness without substantially affecting the energy density within each electroactive polymer layer, which would enable manufacturing of thinner devices without compromising their performance and/or of devices having remarkably improved charge -storage density.

SUMMARY OF THE INVENTION [0008] The present invention solves these objects with the subject matter of the claims as defined herein. The advantages of the present invention will be further explained in detail in the section below and further advantages will become apparent to the skilled artisan upon consideration of the invention disclosure.

[0009] This invention describes a thin film charge -storage device, wherein one of the electroactive polymers exists in an ionic form in the discharged state, in which it includes a mobile counter-ion of the same polarity that it will accept during the charging process. Thus, in the thin film charge- storage device of the present invention there is only the need for one ion to migrate from one polymer layer through the separator to the second polymer layer, rather than for two ions to migrate from the separator into the two respective polymer layers. The result, for this invention, is that the separator can be substantially thinner (until it merely acts as an ion-transporting separator) and can also be more finely optimized to carry the single ionic species.

[0010] In particular, the present invention relates to comprising an n-type electroactive polymer layer, a p-type electroactive polymer layer and a separator between the electroactive polymer layers, wherein, in a discharged state of the thin film charge-storage device, one of the p-type or the n-type electroactive polymers has a repeating unit comprising a covalently attached ionic group which is ionically bound to a mobile counter- ion.

[0011] In a further aspect, the present invention relates to a method of manufacturing a thin film charge-storage device comprising an n-type electroactive polymer layer, a p-type electroactive polymer layer and a separator between the electroactive polymer layers, wherein the method comprises a step of depositing one of the p-type or the n-type electroactive polymers in a state, wherein its repeating units comprise a covalently attached ionic group which is ionically bound to a mobile counter-ion.

[0012] Preferred embodiments of the thin film charge-storage device and the manufacturing method according to the present invention and other aspects of the present invention are described in the following description and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 a schematically illustrates the general architecture of a conventional electroactive polymer-based charge-storage device and the electron flow and ion movement during charge.

[0014] FIG. 1 b schematically illustrates the electron flow and ion movement during discharge.

[0015] FIG. 2a schematically illustrates the function of a charge -storage device comprising an anionic p-type electroactive polymer according to the present invention during charge.

[0016] FIG. 2b schematically illustrates the electron flow and ion movement during discharge.

[0017] FIG. 3a schematically i!!ustrates the function of a charge-storage device comprising a cationic n-type electroactive polymer according to the present invention during charge.

[0018] FIG. 3b schematically illustrates the electron flow and ion movement during discharge. DETAILED DESCRIPTION OF THE INVENTION

[0019] For a more complete understanding of the present invention, reference is now made to the following description of the illustrative embodiments thereof:

Thin film charge-storage devices

[0020] The present invention relates to a thin film charge-storage device comprising an n- type electroactive polymer layer, a p-type electroactive polymer layer and a separator between the electroactive polymer layers, wherein, in a discharged state of the thin film charge-storage device, one of the p-type or the n-type electroactive polymers has a repeating unit comprising a covalently attached ionic group which is ionical!y bound to a mobile counter-ion.

[0021] The term "electroactive polymer", as used herein, denotes a polymer which exhibits variable physical and/or chemical properties resulting from an electrochemical reaction within the polymer upon application of an external electrical potential, and must be thus distinguished from electrochemicaily inert materials or insulating materials, such as conventional electrolytes and porous separator layer supports.

[0022] In general, the electroactive polymer comprising a covalently bound ionic group exhibits repeating units containing both an electroactive unit and a unit comprising the covalently bound ionic group to which a mobile counterion is attached. It is to be noted that both units may be separate or be combined within a single unit. The wording "electroactive unit" as used herein, generally denotes a structural motif in the electroactive polymer which is capable of accepting (n-type) or donating (p-type) an electron in the presence of an electrical field so as to carry the electrical charge -1 or +1 , which may be present in the form of unpaired electrons, the latter often residing in the HOMO (for a cation) or LUMO (for an anion) of the molecular species.

[0023] For example, the electroactive polymer comprising the covalently bound ionic group may be described by the following general formula (1 ): wherein at least one of the groups Yi to Y3 comprise an electroactive (n-type or p-type) unit and at least one of the groups Yi to Y3 comprise a covalently bound ionic group to which a mobile counter-ion is attached; wherein both the electroactive unit and the ionic group may be separate or be combined within a single unit; and wherein the group Yi to Ya neither comprising the electroactive unit nor the covalentiy bound ionic group, if present, may be a single bond or an in-chain conjugated aromatic or heteroaromatic group, for example.

[0024] Apart from the presence of a covalentiy bound ionic group in one of the n-type or p-type polymers, the material providing for the electroactive units may be selected from electroactive substances known in the art.

[0025] For instance, the p-type electroactive polymers are not particularly limited and may be appropriately selected from standard electron donating conjugated organic polymers which are readily oxidized in relation to a high workfunction electrode so as to form stable oxidation products. Suitable compounds will be known to the person skilled in the art and are described in the literature. In a preferred embodiment, the p-type conjugated organic polymer is a co-polymer including alternating, random or block copolymers. As exemplary p-type conjugated organic polymers, polymers selected from conjugated hydrocarbon or heterocyclic polymers may be mentioned. As examples, in-chain conjugated (co- }polymers comprising as monomer units one or more selected from the group consisting of acene, aniline, azulene, benzofuran, fluorene, furan, indenofluorene, indole, phenylene, pyrazoline, pyrene, pyridazine, pyridine, diarylalkylamine, triarylamine, phenylene vinylene, 3-substituted thiophene, 3,4-bisubstituted thiophene, selenophene, 3-substituted selenophene, 3,4-bisubstituted selenophene, bisthiophene, terthiophene, bisselenophene, terselenophene, thieno[2,3-b]thiophene, thieno[3,2-b]thiophene, benzothiophene, benzo[1 ,2-b:4,5-b']d!thiophene, isothianaphthene, monosubstituted pyrrole, 3,4- bisubstituted pyrrole, 1 ,3,4-oxadiazoles, isothianaphthene, and derivatives thereof may be mentioned, with the proviso that either singly or in combination the chosen monomer(s) can be oxidized by the removal of one or more electrons to form a stable oxidation product (e.g. a positively charged species). Preferred examples of such p-type polymers are in-chain conjugated (co-)polymers of monomers selected from at least one, more preferably at least two of the group of fluorenyl derivatives, phenylene derivatives, aniline derivatives, dialkylarylamines, diarylalkylamines, diarylamines, triarylamines and heteroaromatic hydrocarbons. Where appropriate, the above-defined groups may be pendant or be present in the backbone of the polymer. It is further understood that the p- type conjugated organic polymers may also consist of a mixture of a plurality of the above- mentioned polymers.

[0026] The n-type electroactive polymers are also not particularly limited and may be suitably selected from electron accepting materials which are readily reduced in relation to a low workfunction electrode so as to form stable reduction products. Suitable n-type polymers will be known to the skilled artisan and may consist of a mixture of a plurality of electron accepting materials. Preferred examples of n-type organic semiconductors are in- chain conjugated (co-)poiymers of monomers selected from the group of fluoreny! derivatives, heteroaromatic hydrocarbons (such as e.g. benzothiadiazoles and its derivatives, triazine derivatives (e.g. 1 ,3,5-triazine derivatives), azafluorene derivatives, or quinoxalines), conjugated aromatic hydrocarbons (e.g. arenes, acenes), and carbonyl- based monomers (such as fluorenone derivatives), with the proviso that either singly or in combination the chosen monomer(s) can be reduced by accepting one or more electrons to form a stable reduction product (e.g. a negatively charged species).

[0027] The separator is not particularly limited and may be made of known materials that are chemically and electrochemica!ly unreactive with respect to the charges and to the electrode polymer materials in their neutral and charged states. Typically, the separator contacts the n-type and p-type electroactive polymer layers such that the transport of ions is facilitated. As suitable materials, porous polymeric materials (e.g. polyethylene, polypropylene, polyester, PTFE or cellulose-based polymers), ion-conductive polymer membranes (e.g. Nation™), (electronically non-conductive) gel electrolytes (e.g. polymers, copolymers and oligomers having monomer units selected from the group consisting of substituted or unsubstituted vinylidene fluoride, urethane, ethylene oxide, propylene oxide, acrylonitrile, m ethyl meth aery late, alkylacrylate, acrylamide, vinyl acetate, vinylpyrrolidinone, tetraethylene glycol diacrylate, phosphazene and dimethylsiioxane) and cellulose-based gel electrolytes may be mentioned. Polymers, when used as a separator, should be resistant towards dissolution by the electrolyte, which may be appropriately achieved by methods known to the skilled artisan (e.g. by suitable selection of materials or by cross-linking).

[0028] It is to be understood that electroactive polymer as used in the present invention may generally comprise cross-linking units, i.e. functional groups which enable to bond the polymer chains, which may be appropriately chosen by the skilled artisan.

[0029] In addition, the electroactive polymer layers may comprise further additives, such as e.g. plasicizers, surfactants, cross-linking agents or low-molecular weight compounds.

[0030] While the electroactive polymer layers may consist of the electroactive polymers, the layers may comprise further materials that are conventionally used in the preparation of polymeric films for thin film devices. For example, electroactive polymer layers may be combined with one or more layers that may be polymeric or non-polymeric (e.g. a current collector layer) and/or comprise material embedded into the respective polymer films (e.g. a conductive material for electrode connection etc.). Suitable materials for current collector layers include material that is selected from the group consisting of porous graphite, porous, highly doped inorganic semiconductor, highly doped conjugated polymer, carbon nanotubes or carbon particles dispersed in a non-conjugated polymer matrix, aluminum, silver, platinum, gold, palladium, tungsten, indium, zinc, copper, nickel, iron, lead, lead oxide, tin oxide, indium tin oxide, graphite, doped silicon, doped germanium, doped gallium arsenide, doped polyaniline, doped polypyrrole, doped polythlophene, and their derivatives. If the electroactive polymer layers themselves serves as the current collectors, conductive particles (such as carbon nanotubes or carbon particles, for example) may be dispersed in the polymer layers at a concentration higher than a percolation threshold concentration. In addition to the above, a substrate layer may be provided adjacent to the electroactive polymer layers, e.g. as a mechanical support.

[0031] The thin film charge-storage device according to the present invention may also comprise additional layers, such as one or more encapsulation layers, for example.

[0032] Preferably, the thin film charge-storage device of the present invention is a battery/supercapacitor hybrid.

[0033] The electrolyte for use in the thin film charge-storage device of the present invention is not particularly limited and may be suitably selected by the skilled artisan depending on the chosen separator and polymer materials as well as the mobile ionic species. While not being limited thereto, it may be preferable to use electrolytes that are liquid at room temperature (25°C). As examples thereof, electrolyte salts dissolved in appropriate solvents as commonly used in the art or ionic liquids that are typically liquid below 100 °C may be mentioned, the latter including, but not being limited to ammonium-, imidazolium-, phosphonium-, pyridinium-, pyrrolidinium-, and sulfonium-based ionic liquids. As the use of ionic liquids allows volatile and hazardous conventional solvents to be eliminated and improves the operational stability of these devices, ionic liquids may be preferable as liquid electrolytes.

[0034] The thickness of each of the n-type and p-type electroactive layers containing the continuous, solid and porous electroactive polymer material may be chosen appropriately depending on the required purpose and is typically in a range of between 0.05 to 500 pm.

[0035] The separator layer thickness may likewise be appropriately selected by the skilled artisan depending on the purpose. In conventional devices, the separator thickness is typically about one third or more of the overall thickness of the electroactive layers since the separator must store both the anionic and cationic mobile species in the discharged state of the device. In the present invention, the separator layer thickness may be reduced to a thickness of 25% or less, usually 20% or less, in embodiments 15% or less of the overall thickness of the electroactive layers without substantially affecting the energy density within each electroactive polymer layer, which enables manufacturing of thinner devices without compromising their performance and which have remarkably improved charge-storage density (up to 50% increase). Typically, the separator thickness is 20 μηι or less, preferably 10 m or less.

Devices comprising p-type polymers with a covaientiy bound anionic group

[0036] In one embodiment of the present invention, the p-type polymer exhibits in a discharged state of the thin film charge-storage device a repeating unit comprising a covaientiy bound anionic group to which a mobile cation is attached. In this configuration, it is preferable that the n-type polymer is substantially non-ionic in the discharged state of the thin film charge-storage device.

[0037] An exemplary configuration of a thin film charge-storage device according to said embodiment and its functioning are illustrated in Figures 2A and 2B, which show the electron flow and ion movement during charge (Fig. 2A) and discharge (Fig. 2B). In the discharged state of the thin film charge-storage device, the p-type polymer P _N ^" in layer (4a) comprises a covaientiy bound anionic group to which a mobile cation is attached. When charging, the mobile cations move towards the n-type polymer layer (2) to counterbalance the growing negative charge formed by electrochemical reduction (Fig. 2A). During discharge, the mobile cations move towards the p-type polymer and bind to their covaientiy bound anionic groups (Fig. 2 B). Thus, in the present invention, there is only the need for one ionic species to migrate from one polymer layer through the separator to the other. As a result, the separator may be substantially thinner and may also be more finely optimized to carry the single ionic species.

[0038] The mobile cation is not particularly limited any may be suitably selected by the skilled artisan depending on its stability, mass and/or ease of movement. Suitable organic cations may be derived from known imidazolium derivatives, pyrrolidinium derivatives, isoquinolinium derivatives, alkylsulfonium derivatives, ammonium derivatives, phosphonium derivatives and aminium derivatives typically used in ionic liquids. Specific examples thereof are disclosed in S. Zhang et al., J. Phys. Chem. Ref. Data 2006, 35(4), 1477-1481. Preferably, the mobile cation is selected from any of imidazolium derivatives, pyrrolidinium derivatives, phosphonium derivatives, pyridinium derivatives, asymmetric aliphatic quaternary ammonium derivatives, guanidinium derivatives. As an alternative to organic cations, monovalent or divalent metal cations (including but not limited to alkali metal cations or alkaline earth metal cations) may be advantageously used, of which Na ⁺ , Li ⁺ , Mg ²⁺ , Ca ^s+ and Zn ²⁺ are preferred examples. Li ⁺ is particularly favourable as it is lightweight, relatively non-toxic and may be used with a variety of known separator materials designed to selectively transport Li ⁺ . Divalent metal cations, such as Mg ²⁺ , on the other hand, are capable of transporting two charges in their +11 state, which enables very fast ion movement, particularly when compared to bulkier organic ion species.

[0039] In general, the anionic group covalently bound in the repeating unit may be an in- chain or a pendant anionic group, a pendant anionic group is preferable.

[0040] The anionic group is not particularly limited as long as it is stable and capable of electrically neutralizing the mobile cation. Preferably, the anionic group is selected from any of a carbanion, -CCV.-SCV, -O-, -BF ₃ ^" , -NCF ₃ -, -NCN ^" , or -S ^" .

[0041] In this embodiment, the p-type polymer generally comprises repeating units containing both an eiectroactive unit (i.e. a structural motif in the eiectroactive polymer which is capable of donating (p-type) an electron in the presence of an electrical field so as to carry the electrical charge +1) and a unit comprising covalently bound anionic group to which a mobile cation is attached, wherein both units may be separate or be combined within a single unit, as will be further explained below. In addition, while the eiectroactive unit is usually in the main chain of the polymer, it may alternatively or additionally be also provided pendant from the polymer.

[0042] In a preferred embodiment, the repeating unit comprises one or more of a fluorenyl derivative, a phenyiene derivative, an aniline derivative, a dialkylarylamine, a diary!alkyiamine, a diarylamine, a triarylamine, a substituted or unsubstituted in-chain conjugated aromatic hydrocarbon and/or a heteroaromatic hydrocarbon. More preferably, the repeating unit comprises an arylamine derivative and/or a fluorenyl derivative.

[0043] Preferable examples of arylamine derivatives are shown in the following general formulae (2-1 ) to (2-3):

[0044] Herein, Ri to F½ may be independently selected from hydrogen, a halogen, a d- C ₂ o alkyi, a Ci-C ₂₀ alkoxy, a C1-C20 haloafkyl or a substituted or unsubstituted C ₆ -C ₃ o aryl group, with hydrogen being preferable; Zi and Z ₂ independently represent a C ₁ -C ₂ 0 alkylene group, a C1-C20 ether group, a Ci-C ₂₀ haloalkylene or a substituted or unsubstituted C-6-C30 aryl group, at least one of the groups comprising one or more anionic groups which are preferably selected from any of a carbanion, -CO2VSO3 ^" , -O ^" , -BF3 ^" , - NCF3 ^" , -NCN ^" , or -S ^~ as a substituent.

[0045] While in the examples above, the redox active unit is electrically neutral and there is a separate negative charge provided for by the anionic group, there may be examples wherein the negatively charged species is also the species that is oxidized. Here, the negative charge must be stabilized to an extent where unwanted chemical transformation is prevented while still enabling to be electrochemically ionized. This may be achieved by use of an electronegative heteroatom (e.g. oxygen, nitrogen or sulphur) to enable the energy level of the electron to be low enough to enable a sufficient energy difference with the n-type material or by the use of aromatic derealization, provided that the resulting unpaired electron (radical) is also sufficiently stable that it does not undergo unwanted chemical transformation. Several stable radicals are known in the art, such as galvinoxyl and its derivatives, for example. While not being limited thereto, preferred carbanionic structures are exemplified below in conjunction with general formulae (2-4) and (2-5):

[0046] Namely, a preferred embodiment of a substituted or unsubstituted in-chain conjugated aromatic hydrocarbon includes a repeating unit comprising a stabilized carbanion according to general formula (2-4) that has a low-lying HOMO:

(2-4) [0048] Herein, F½ to R ₁₆ and Ris may be independently selected from hydrogen, a halogen, a Ci -C ₂₀ alkyl, a Ci -C ₂₀ aikoxy, a Ci-C ₂₀ haloalkyl or a substituted or unsubstituted Ce-Cao aryl group, with hydrogen being preferable; D is selected from any of oxygen, sulfur or C(CN)2; and Ri ₇ represents a C1 -C20 haloalkyl, a Ce-C ₃ o aryl group or a second redox-active unit, each of which may be unsubstituted or substituted by one or more electron withdrawing groups, such as e.g. a halogen, preferably fluorine.

[0049] Such systems can be formed in-situ from more stable and readily available material according to the following reaction scheme, wherein L represents a leaving group which may be suitably selected by the skilled artisan, such as CO2 or formaldehyde, for exam le:

[0050] For example, using CO2 as L enables decarboxylation by heating. The material could be encapsuiated after removal of the leaving group L so that the CO2 could be released, or it could be simply allowed to remain in the battery or to diffuse slowly out.

[0051] A repeating unit comprising a structural motif which allows stabilization through aromatic derealization is shown in general formula (2-5):

[0052] In formula (2-5), R ₂₂ to R29 may be independently selected from hydrogen, a halogen, a C1-C20 alkyl, a C1-C20 aikoxy, a C1-C20 haloalkyl or a substituted or unsubstituted C-6-C30 aryl group, with hydrogen being preferable; and Ar ¹ and Ar ² may be independently selected from a C6-C30 aryl group, which may have one or more substituent(s), preferably (a) substituent(s) selected from a C1-C20 alkyl group. In a further preferred embodiment, Ar ¹ and Ar ² are trimethylphenylene groups.

[0053] Upon oxidation, the resulting radical species may be stabilized according to the following scheme:

[0054] As mentioned above with respect to general formula (1), the pendant ionic group does not need to be attached directly to the electroactive unit, and the eiectroactive polymer may comprise the covalently attached ionic group and the redox-active group in two different structural motifs or co-monomers. A preferred example of such as structure is general formula (2-6), which represents a combination of an arylamine derivative and/or a fluorenyl derivative:

[0055] Herein, R ₃ o to F ₄ may be independently selected from hydrogen, a halogen, a Ci- C-20 alkyl, a Ci-C ₂₀ alkoxy, a C1-C20 haioalkyl or a substituted or unsubstituted Ce-Cao aryl group, with hydrogen being preferable; R45 may independently represent any of hydrogen, a C1-C20 alkyl, a C1-C20 alkoxy, a C1-C20 haioalkyl or a substituted or unsubstituted C6-C30 aryl group or a second redox-active unit, with a C3-C18 alkyl group or C1-C20 haioalkyl having a solubiiising function being preferred; FUe may independently represent any of hydrogen, a C1-C20 alkyl, a C1-C20 alkoxy, a Οι-Ο ₂ ο haioalkyl or a substituted or unsubstituted Ce-Cao aryl group or a second redox-active unit, a substituted or unsubstituted C6-C30 aryl group being preferred; and Z ₃ represents a group selected from a C1-C20 alkylene group, a C1-C2 ₀ ether group, a C1-C2 ₀ haloalkylene or a substituted or unsubstituted C6-C30 aryl group, the group comprising one or more anionic groups which are preferably selected from any of a carbanion, -CO2VSO3 ^" , -O ^" . -BF ₃ ^" , -NCF3 ^" , -NCN ^" , or -S ^" as substituent(s).

[0056] In a preferred embodiment, which may be appropriately combined with any of the above-mentioned embodiments, the covalently attached ionic groups form the electroactive units of the electroactive polymer, which may be accomplished by positioning at least two electroactive units in the polymer so that upon oxidation, a ir-bond rearrangement is achieved rather than leaving an unpaired electron (in analogy to the mechanism described with respect to genera! formula (2-5)). This can enable higher charge densities and also a higher electrochemical stability.

[0057] As an example thereof, ionic groups formed by a quinone derivative, preferably an o- or p-quinone derivative may be mentioned. As particularly preferred examples thereof, structural formulae (A-1) and (A-2) are given:

[0058] As such anionic groups also provide for the electroactive species, the choice of materials for the polymer main chain may be widened. For example, a fluorenyi derivative according to general formula (2-7) may be used, as the sole monomer or in combination with other co-monomers without electroactive units:

[0059] Herein, R47 to F½ may be independently selected from hydrogen, a halogen, a Ci- C20 alkyl, a C1-C20 alkoxy, a C1-C20 haloaikyl or a substituted or unsubstituted C-6-C30 aryl group, with hydrogen being preferable; F½ may independently represent any of hydrogen, a C1-C20 alkyl, a C1-C20 alkoxy, a C1-C20 haloaikyl or a substituted or unsubstituted C6-C30 aryl group or a second redox-active unit, with a C3-C18 alkyl group or C1-C20 haloaikyl group having a soiubilising function being preferred; and Z4 represents an anionic quinone derivative or a group selected from a C1-C20 alkylene group, a C1-C20 ether group, a Ci- C20 haloalkylene or a substitued or unsubstituted C6-C30 aryl group, the selected group comprising an anionic quinone derivative; wherein the anionic quinone derivative is preferably selected from an anionic o- or p-quinone derivative, further preferably from any of groups (A-1 ) or (A-2). [0060] As an alternative to quinone derivatives, a preferred example of an in-chain conjugated aromatic hydrocarbon is given by means of general formula (2-8), which likewise allows for ττ-bond rearrangement upon oxidation:

[0061] Herein, R ₅₄ to Rei may be independently selected from hydrogen, a halogen, a Ci- C-20 alkyl, a C1-C20 alkoxy, a C1-C20 haloalkyl or a substituted or unsubstituted C6-C30 aryl group, with hydrogen being preferable; and Z5 and Z ₆ are selected from any of -O ^" or -S ^~ , preferably -O ^" .

[0062] It is to be noted that the structural formulae (2-1) to (2-5), (2-7) and (2-8) may be comprised in the p-type polymer the sole monomers, as substructures of monomers, or as co-monomers or substructures thereof which form a part of the p-type polymer (which may be an alternating, random or block copolymer). Devices comprising n-type polymers with covalently bound cationic group

[0063] In an alternative embodiment of the present invention, the n-type polymer exhibits in a discharged state of the thin film charge-storage device a repeating unit comprising an covalently attached cationic group to which a mobile anion is ionically bound, in this configuration, it is preferable that the p-type polymer is substantially non-ionic in the discharged state of the thin film charge-storage device.

[0064] An exemplary configuration of a thin film charge-storage device according to this embodiment and its functioning are illustrated in Figures 3A and 3B, which show the electron flow and ion movement during charge (Fig. 3A) and discharge (Fig. 3B). In the discharged state of the thin film charge-storage device, the p-type polymer PP ⁺ in layer (2a) comprises a covalently attached cationic group to which a mobile anion is ionically bound. When charging, the mobile anions move towards the p-type polymer layer (4) to counterbalance the growing positive charge formed by electrochemical oxidation (Fig. 3A). During discharge, the mobile anions move towards the n-type polymer and bind to their covalently attached cationic groups (Fig. 3B), thereby also only requiring one ionic species to migrate from one polymer layer through the separator to the other. [0065] The mobile anion is not particularly limited any may be suitably selected by the skilled artisan depending on the purpose. Suitable anions include, but are not limited to chloride, perch!orate, bromide, iodide, tetrafluoroborate, 1 -carbon icosahedral, methylcarbonicosahedral, ethylcarbonicosahedrai, propylcarbonicosahedral, butylcarbonicosahedral, hexachloride-1 -carbon icosahedral, hexabromide-1 -carbon icosahedral, bis-(2-methy!lactato)borate, bis(oxalato)borate, bis(malonato)borate, bis(salicylato)borate, tetraphenylborate, tetrakis-((4-methyl) phenyl) borate, tetrakis-((4- trifluoromethyl)phenyl)borate, tetrakis-((4-trimethyisilyl)phenyl)borate, tetrakis-(3,5- bis(trifluoromethyl)phenyl)borate, tetrakis-((4-dimethyI-(3,3,3-trifiuoropropyl)- silane)phenyl)borate, tetrakis-((4-dimeth-heptylsilane)phenyl)borate, tetrakis-((4- perfluorohexyl)pheny!)borate, tetrakis-(3,5-bis(trifluoromethyl)phenyl)borate, tetrakis-((4- dimeth-perfluoroheptylsiiane) phenyl) borate, nitrite, dicyanoamides, nitrate, bis(methylsulfonyl)imides, 2,2,2-(trifluoromethylsulfonyl)acetamide, perfluoroethylimide, bis((trifluoromethyl)sulfonyl)imides, bis((trifluoromethyl)sulfonyloxyl)imides, bis((perfluoroethane)sulfonyl)imides ₅ mesylate, sulfate, trifluoromethanesulfinates, trifluoromethanesu!fonates, tosylate, octylsulfate, perfluorobutylsulfinate, perfiuorobutylsulfonate, phosphate, hexafluorophosphate, acetate, trifluoroacetates, heptafluorobutanoates, tri(thfluoromethyIsulfonyl)methyl, hydrofluoride anions, tetrach!oroaluminate, hexafluoroarsenic, hexafluoroniobium, hexafluoroantimony, and hexafluorotantalum. Preferred examples include fluoroalky!sulfonyiimides (e.g. bis((triffuoromethyl)sulfony!)imide (TFSI), fiuoroalkylsulfonates (e.g. trifluoromethansulfonate ( Tf)), tetrafluoroborate (BF ₄ ), hexafluorophosphate (PFe ) and hexafluoroantimony (SbFe ^" ).

[0066] In general, while the covalently bound cationic group may be an in-chain or a pendant cationic group, a pendant cationic group is preferable.

[0067] The cationic group is not particularly limited as long as it is stable and capable of electrically neutralizing the mobile anion. For example, the cationic group may be a nitrogen-containing cationic group derived from imidazolium derivatives, pyrrolidinium derivatives, isoquinolinium derivatives, a!kylsulfonium derivatives, ammonium derivatives, phosphonium derivatives and aminium derivatives. It is preferable that the cationic group is a nitrogen-containing cationic group selected from pyridinium, imidazolium, -NF , and derivatives thereof, R being independently selected from a C1 -C20 alkyl, a C1 -C20 alkoxy, a C1 -C20 haloalkyl or a substituted or unsubstituted C6-C30 aryl group.

[0068] In this embodiment, the n-type polymer generally comprises repeating units containing both an eiectroactive unit (i.e. a structural motif in the eiectroactive polymer which is capable of accepting an electron in the presence of an electrical field so as to carry the electrical charge -1) and a unit comprising a covalently attached anionic group to which a mobile counter-cation is ionically bound, wherein both units may be separate or be combined within a single unit, as will be further explained below. In addition, while the electroactive unit is usually in the main chain of the polymer, it may alternatively or additionally be also provided pendant from the polymer.

[0069] In a preferred embodiment, the n-type polymer is an in-chain conjugated {copolymer of monomers selected from the group of fluorenyl derivatives, heteroaromatic hydrocarbons (such as e.g. benzothiadiazoles and its derivatives, triazine derivatives (e.g. 1 ,3,5-triazine derivatives), azafluorene derivatives, quinoxalines), conjugated aromatic hydrocarbons (e.g. arenes, acenes), and carbonyi-based monomers (such as fluorenone derivatives).

[0070] It is particularly preferred that the repeating unit constituting the n-type polymer comprises a fluorenyl derivative and/or a heteroaromatic hydrocarbon, the heteroaromatic hydrocarbon being preferably selected from benzothiadiazole derivatives, triazine derivatives, azafluorene derivatives, or quinoxalines.

[0071] Examples thereof include, but are not limited to structures according to the following general formulae (3-1) to (3-3):

wherein R ₆ 2 may be selected from hydrogen, a halogen, a C1-C20 alkyl, a C1-C20 alkoxy, a C1-C20 haloalkyl or a substituted or unsubstituted Ce-C3o aryl group, with hydrogen being preferable; and wherein Xi is represented by a group -Sp-A; with Sp being a spacer group selected from a single bond, a C1 -C20 alkylene, a C1 -C20 ether group, a G-C20 haloalkylene group or a substituted or unsubstituted C6-C30 arylene group, the spacer group being preferably an C1-C10 alkylene group; and A being a cationic group, preferably a nitrogen-containing cationic group selected from pyridinium, imidazolium, -NFV, and derivatives thereof, R being independently selected from a C1-C20 alkyl, a C1 -C20 alkoxy, a C1-C20 haloalkyl or a substituted or unsubstituted Ce-Cao aryl group;

(3-2) wherein R ₆ 3 to Res may be selected from hydrogen, a halogen, a C1-C20 alkyl, a C1-C20 alkoxy, a C C-20 haloalkyl or a substituted or unsubstituted C-6-C30 aryl group, with hydrogen being preferable; R ₆ g is a group capable of accepting an electron in the presence of an electrical field; and wherein X ₂ is represented by a group -Sp-A; with Sp being a spacer group selected from a single bond, a C1-C20 alkylene, a C1-C20 ether group, a Ci-C ₂₀ haioalkylene group or a substituted or unsubstituted C6-C30 arylene group, the spacer group being preferably an C1 -C10 alkylene group; and A being a cationic group, preferably a nitrogen-containing cationic group selected from pyridinium, imidazolium, - NR ₃ ⁺ , and derivatives thereof, R being independently selected from a C1-C20 alkyl, a Ci- C20 alkoxy, a C1-C20 haloalkyl or a substituted or unsubstituted C6-C30 aryl group;

wherein R70 to R7? may be selected from hydrogen, a halogen, a C1 -C20 alkyl, a C1 -C20 alkoxy, a Ci-Cao haloalkyl or a substituted or unsubstituted C6-C30 aryl group, with hydrogen being preferable; and wherein X ₃ is represented by a group -Sp-A; with Sp being a spacer group selected from a single bond, a C1-C20 alkylene, a C1 -C20 ether group, a Ci-C ₂₀ haioalkylene group or a substituted or unsubstituted C-6-C30 arylene group, the spacer group being preferably an C1 -C10 alkylene group; and A being a cationic group, preferably a nitrogen-containing cationic group selected from pyridinium, imidazolium, - NR ₃ ⁺ , and derivatives thereof, R being independently selected from a C1-C20 alkyl, a Ci- C20 alkoxy, a C1-C20 haloalkyl or a substituted or unsubstituted Ce-C ₃ o aryl group.

[0072] It is to be noted that the structural formulae (3-1) to (3-3) may be comprised in the n-type polymer the sole monomers, as substructures of monomers, or as co-monomers or substructures thereof which form a part of the n-type polymer (which may be an alternating, random or block copolymer).

[0073] It will be appreciated that the preferred features specified above may be combined in any combination, except for combinations where at least some of the features are mutually exclusive. Methods of manufacturing of thin film charge-storage devices

[0074] The thin film charge-storage device according to the present invention may be manufactured by conventional processes known in the art.

[0075] For example, the n-type and/or p-type electroactive polymer layers may be manufactured by polymerizing one (or more) monomer(s) of the desired conjugated by electropolymerization or chemical polymerization. Alternatively, the n-type and/or p-type electroactive polymer layers may be fabricated by a solution deposition or coating process, which is often followed by a heating treatment in order to further enhance the densification and uniformity of the thin film. The method of film deposition may include thermal deposition, vacuum deposition, laser deposition, screen printing, printing, imprinting, spin casting, dipping, ink jetting, roll coating, flow coating, drop casting, spray coating, and/or roll printing, for example.

[0076] Advantageously, a vast majority of the p-type and n-type electroactive polymers having a repeating unit comprising an ionic group as used in the thin film charge-storage device of present invention and as further described in the above embodiments are sufficiently stable in typical deposition environments to be sufficiently unreactive so that they can be deposited in their charged state.

[0077] Accordingly, a further aspect of the present invention relates to a method of manufacturing a thin film charge-storage device comprising an n-type electroactive polymer layer, a p-type electroactive polymer layer and a separator between the electroactive polymer layers, wherein the method comprises a step of depositing one of the p-type or the n-type electroactive polymers in a state, wherein its repeating units comprise a covalently attached ionic group to which a mobile counter-ion is ionically bound.

[0078] In this embodiment, it is preferable that the n-type and/or p-type electroactive polymer layers are deposited by a solution deposition or coating process as specified above.

[0079] In conventional manufacturing methods, the n-type/separator/p-type structure is typically deposited first, optionally partly encapsulated, and the separator is soaked with electrolyte thereafter in order to provide for the ion reservoir. Advantageously, the method of the present invention simplifies the manufacturing of thin film charge-storage devices as the required mobile ions are already provided with the respective n- or p-type electroactive polymer layer.

[0080] it will be appreciated that the method of the present invention may employ any of the preferred features specified above with respect to the description of the devices and the n-type and p-type eiectroactive polymers, and that the preferred features may be combined in any combination, except for combinations where at least some of the features are mutually exclusive.

REFERENCE NUMERALS

1 : cathode current co!!ector/substrate

2: n-type polymer layer

2a: layer comprising cationic n-type polymer in discharged state

3: separator

4: p-type polymer layer

4a: layer comprising anionic p-type polymer in discharged state

5: anode current collector/substrate