The present invention relates to an optoelectronic foil and a method for the production thereof.

In terms of design, the optoelectronic foil consists of a flexible polymer foil substrate and a transparent electrode. It is the basis for the construction of a wide array of optoelectronic devices that are produced on said foils using a variety of techniques. Optoelectronic devices, for the construction of which optoelectronic foils are used, include flexible emission displays (OLED, QD LCD), flexible photovoltaic devices, touch screen sensors, flexible random access memory (RAM) and gas sensors.

The disadvantage of optoelectronic flexible foils lies in the poor tightness of the flexible substrate constituted by polymer foils with a high oxygen and water permeability coefficient, which result in the short lifespan of optoelectronic devices. Especially devices containing organic materials in active layers, for example OLEDs (Organic Light Emitting Diodes) are sensitive to weather conditions. Moisture and oxygen penetration from the air cause the degradation of the active material, which, as a result, precludes the optoelectronic device from operating.

Various technologies are known for the production of protective layers in the structure of optoelectronic foils designed to extend the lifespan of optoelectronic devices, including:

- "Dam-and-fiH" encapsulation technique. During this process, a high viscosity fluid is distributed, forming a rectangular barrier around the device (e.g. an OLED). Said fluid is distributed during the droplet application process so as to fill the space between the substrate and the barrier film within the barrier. This method is characterized by simplicity and high stability;

- technique of sealing using a thin multi-layer foil, i.e. "thin-film-encapsulation" (TFE).

The most common TFE technologies include plasma-enhanced chemical vapor deposition (PECVD) and atomic layer deposition (ALD);

- Plasma-enhanced chemical vapor deposition (PECVD) involves preparation of an inorganic-and-inorganic or organic-and-organic barrier, with the process typically using silicon nitride or silicon dioxide; the advantage of this technique lies in the low temperature process (below 600°C), and the possibility of deposition of non- equilibrium phases, as well as the relatively high purity of the resulting coatings; - atomic layer deposition technique, (ALD), which involves depositing a barrier film; this technique uses e.g. aluminium oxides and nitrides for deposition; the advantage of this method is that it allows for obtaining coatings characterised by relatively good tightness.

Moreover, some techniques that are known for improving barrier characteristics and general sealing of a FOLED (Flexible Organic Light Emitting Diode) display, involve using ultra-thin metal or glass foils. The advantage of this type of solutions is the achievement of foils with good gas permeability properties, while it is their disadvantage that the foils obtained are matte, opaque and easily damaged.

Further, patent literature discloses structures of conductive materials used for the construction of optoelectronic devices.

International patent application WO2015/179834A1 discloses a structure of a conductive film consisting of silver (Ag) in an amount of no less than 80% of the total atomic content of the conductive film and a conductive metal selected from the group consisting of: Al, Ti, Ni, Cr, Au, Mg, Ta, Ge in an amount of no more than 20% of the total atomic content of the conductive film. The manufacturing process of the electrically conductive layer comprises the co-deposition of gold, copper and a conductive metal on a substrate to form a continuous conductive film. WO2015/179834A1 , however, does not provide information on the method for preparing a barrier layer to limit the moisture or oxygen penetration into the conductive film.

Therefore, it is desirable to provide a flexible optoelectronic foil structure with improved barrier properties against particles of gas and water vapour, which would allow for the manufacture of optoelectronic devices with an extended lifespan without deterioration of the transparency of the entire foil material. It is also desirable to provide the optoelectronic foil, which would be useful for both, passive devices incorporating barrier solutions and active optoelectronic devices including flexible, transparent electrodes.

The invention relates to an optoelectronic foil characterised in that it comprises a substrate and a conductive layer comprising at least one oxide layer and at least one metal layer, wherein between the conductive layer and the substrate of the foil there is a barrier layer comprising at least one material selected from the group consisting of silicon oxides (SiOx), aluminium oxides (AI2O3, AIOxNy), titanium oxides (TiOx), silicon oxynitrides SiON, silicon nitrides (Si3N ₄ , SiNx), organic silicon compounds (SiCxHy), zirconium oxide (Zr02), hafnium oxide (HfO2), chromium oxides (CrO, Cr203, Cr02, Cr03, CrOs) and parylene.

Preferably, the barrier layer is a monolayer structure.

Preferably, the barrier layer is a multi-layer structure consisting of at least two sublayers stacked one on the other within the barrier layer and made of different material.

Preferably, the substrate is made of at least one plastic selected from the group consisting of: polyethylene terephthalate (PET), polyethylene naphthalene (PEN), polyethylene (PE), polypropylene (PP), polyethersulfone (PES), polyimide (PI), polystyrene (PS), ethylene/tetrafluoroethylene (ETFE) and parylene.

Preferably, inorganic nanocomposites are admixed to the substrate.

Preferably, the oxide layer is made of at least one oxide selected from the group consisting of: ZnO, AZO (aluminium zinc oxide), SnO2, IZO (indium zinc oxide), FTO (fluorine tin oxide), ZTO (tin zinc oxide), ITO (tin indium oxide), GZO (zinc gallium oxide), GIO (indium gallium oxide), Ιη2θ3, Sb:SnO2, IO:H (hydrogen indium oxide), CdO, Zn ₂ SnO4, ZnSnOs, Zn ₂ ln ₂ O5, NiOx, NiO _x :Li, TiO _x , ZnS, ZnSe, Te2Os, MoOx, V2O5 and WO3.

Preferably, the oxide layer is a monolayer structure.

Preferably, the oxide layer is a multi-layer structure consisting of at least two sublayers stacked one on the other within the oxide layer and made of different material.

Preferably, the foil comprises one oxide layer.

Preferably, the foil comprises at least two oxide layers.

Preferably, the metal layer is made of at least one material selected from the group consisting of: Al, Ti, Ni, Cr, Au, Mg, Ta, Ge, Ag, Cu, Zr, Pt and W.

Preferably, the foil has a metal layer between adjacent oxide layers.

Preferably, within the conductive layer, the foil has n oxide layers and n-1 metal layers arranged alternately between adjacent oxide layers.

The invention further relates to a method of manufacturing an optoelectronic foil characterised in that a selected surface of the substrate is cleaned and activated onto which a barrier layer is deposited so as to form a barrier layer on said cleaned and activated substrate that comprises at least one material selected from the group consisting of silicon oxides (SiOx), aluminium oxides (AI2O3, AIOxNy), titanium oxides (TiOx), silicon oxynitrides SiON, silicon nitrides (Si3N ₄ , SiN ), organic silicon compounds (SiCxHy), zirconium oxide (ZrO2), hafnium oxide (HfO2), chromium oxides (CrO, Cr203, Cr02, Cr03, CrOs) and parylene, and then a conductive layer comprising at least one oxide layer and at least one metal layer is deposited onto the barrier layer.

Preferably, the barrier layer is formed by depositing one layer of material onto the substrate to form a barrier layer having a monolayer structure.

Preferably, the barrier layer is formed by depositing at least two sublayers of different material onto the substrate to form a barrier layer having a multi-layer structure.

Preferably, the conductive layer is formed so that at least one oxide layer is individually formed one on another on the barrier layer made of an oxide material comprising at least one oxide selected from the group consisting of: ZnO, AZO (aluminum zinc oxide), Sn02, IZO (indium zinc oxide), FTO (fluorine tin oxide), ZTO (tin zinc oxide), ITO (tin indium oxide), GZO (zinc gallium oxide), GIO (indium gallium oxide), Ιη2θ3, Sb:Sn02, IO:H (hydrogen indium oxide), CdO, Zn2SnO4, ZnSnO3, Zn ₂ ln ₂ 05, NiOx, NiO _x :Li, TiOx, ZnS, ZnSe, Τβ2θ3, MoOx, V2O5 and WO3 and at least one metal layer of a material comprising at least one metal selected from the group consisting of: Al, Ti, Ni, Cr, Au, Mg, Ta, Ge, Ag, Cu, Zr, Pt and W.

Preferably, the conductive layer is formed so that on the barrier layer there are individually formed one on another, with the alternating arrangement of oxide layers and metal layers, n oxide layers and n-1 metal layers, where n is a natural number.

Preferably, the conductive layer is formed so that on the barrier layer there are individually formed a first oxide layer, then a metal layer is formed on the first oxide layer, and then a second oxide layer is formed on the metal layer.

Preferably, at least one oxide layer is formed by depositing one layer of oxide material to form an oxide layer having a monolayer structure.

Preferably, at least one oxide layer is formed by depositing at least two oxide sublayers of different material to form an oxide layer having a multi-layer structure.

Preferably, the substrate is cleaned and activated using at least one technique selected from the group consisting of: plasma treatment, corona discharge treatment, carbon dioxide treatment, ultraviolet radiation and ozone treatment, and cleaning with solvents selected from the group consisting of acetone, isopropanol, water, mixture of acetone with water and mixture of isopropanol and water.

Preferably, the barrier layer is deposited onto the substrate using at least one technique selected from the group consisting of atomic layer deposition (ALD), magnetron sputtering, electron-beam sputtering technique and thermal evaporation technique.

Preferably, the conductive layer is deposited onto the substrate using at least one technique selected from the group consisting of atomic layer deposition (ALD), magnetron sputtering, electron-beam sputtering technique and thermal evaporation technique.

An embodiment of the present invention will now be described by way of example with reference to the accompanying drawings, wherein:

Fig. 1 schematically shows a cross-section of the structure of an optoelectronic foil according to one embodiment of the present invention;

Fig. 2 shows a flowchart of the optoelectronic foil manufacturing process, and

Fig. 3 schematically shows a cross-section of the structure of an optoelectronic foil according to another embodiment of the present invention.

The optoelectronic foil according to the invention has a transparency of no less than 50% and is characterised by low water vapor permeability, as the water vapor transmission rate (WVTR) of the optoelectronic foil 10 is between 10 ^"3 and 10 ⁶ g/m ² per day. Due to optoelectronic properties and high transparency, the foil can be used for the manufacture of various devices, including, but not limited to, devices from the field of imaging optoelectronics and photovoltaic optoelectronics. For example, the foil can be used for the manufacture of flexible OLED or QD LCD displays, in photovoltaic systems, including, but not limited to, ultra-thin, transparent photovoltaic cells that can be placed on window panes, computer screens, mobile phones, clothing parts, and other everyday use items. Due to improved barrier properties and improved lifespan, the foil can also be used in the automotive or construction industry.

Fig. 1 schematically illustrates the optoelectronic foil in a cross-section, showing the layered foil construction.

The optoelectronic foil has a substrate 11 with a barrier layer 12 on which a conductive layer 13 comprising at least one oxide layer 131 and at least one metal layer 132 is deposited.

The substrate 11 of the optoelectronic foil 10 may be made of a variety of transparent substrate materials selected from the group consisting of plastics and/or plastics with nanocomposites of inorganic materials. For example, plastics for the substrate 1 may be provided in the form of at least one type of material selected from the group consisting of polyethylene terephthalate (PET), polyethylene naphthalene (PEN), polyethylene (PE), polypropylene (PP), polyethersulfone (PES), polyimide (PI), polystyrene (PS), ethylene/tetrafluoroethylene (ETFE) and polymers evaporated onto the surface from the group of poly-p-xylenes collectively referred to as parylene.

The barrier layer 12 of the foil 10 has a barrier function and prevents against moisture and oxygen penetration from the substrate 11 into the conductive layer 13, thus ensuring a significant reduction of degradation processes of the conductive layer that constitutes the optoelectronic element of the foil 10 and of the active layers of the device that can be deposited onto the optoelectronic foil 10.

The barrier layer 12 consists of at least one material selected from the group consisting of silicon oxides (SiOx), aluminium oxides (A Os, AIOxNy), titanium oxides (TiOx), silicon oxynitrides SiON, silicon nitrides (S13N4, SiNx), organic silicon compounds (SiCxHy), zirconium oxide (Zr02), hafnium oxide (Hf02), chromium oxides (CrO, Cr203, CrO2, CrO3, CrOs) and parylene. More preferably, the barrier layer may consist of at least two different materials selected from the group consisting of silicon oxides (SiOx), aluminium oxides (AI2O3, AIO _x N _y ), titanium oxides (TiOx), silicon oxynitride SiON, silicon nitrides (S13N4, SiNx), organic silicon compounds (SiCxHy), zirconium oxide (ZrO2), hafnium oxide (HfO2), chromium oxides (CrO, Cr2O3, CrO2, CrO3, CrOs) and parylene.

In one embodiment, the barrier layer may take, for example, the form of a monolayer consisting of only one material, such as AI2O3. In another embodiment, the barrier layer may take the form of a monolayer comprising at least two different materials and may be made, for example, of AI2O3 doped with T1O2. In yet another embodiment, the barrier layer 12 may consist of at least two different materials, and it may take the form of a multi-layer comprising, within the barrier layer 12, at least two sub-layers stacked one on the other, wherein each sub-layer may be made of different material or materials. For example, the barrier layer may have two sublayers, where one sublayer is made of AI2O3, and the other sublayer is made of T1O2. Each sublayer within the barrier layer 12 may be of the same or different thickness, preferably in the range between 5 and 500 nm, regardless of the thickness of another sublayer.

Preferably, the barrier layer 12 may comprise two sublayers, each made of a different material, selected from the group of materials listed above. The barrier layer 12 may have a total thickness preferably in the range between 5 and 1000 nm. The conductive layer 13 is an optoelectronic active layer of the foil with conductive properties. The conductive layer 13 comprises at least one oxide layer 131 , 33 and at least one metal layer 132 stacked one on the other.

Moreover, as shown in Fig. 1 , the conductive layer may comprise at least two oxide layers 131 and 133, or more than two oxide layers, separated by metal layers

132 to form a sandwich architecture. All layers 131 , 132, 133 are stacked in the conductive layer 13 one on the other, substantially in parallel.

In each embodiment of the conductive layer 13, for example comprising one or comprising more than one, for example two oxide layers 131 , 133, the oxide layer 131 ,

133 is made of at least one oxide selected from the group consisting of: ZnO, AZO (aluminium zinc oxide), Sn02, IZO (indium zinc oxide), FTO (fluorine tin oxide), ZTO (tin zinc oxide), ITO (tin indium oxide), GZO (zinc gallium oxide), GIO (indium gallium oxide), Ιη2θ3, Sb:SnO2, IO:H (hydrogen indium oxide), CdO, Zn2SnO4, ZnSnO3, Ζη ₂ Ιη2θ5, NiOx, NiO _x :Li, TiOx, ZnS, ZnSe, Te ₂ 03, MoOx, V2O5 and WO3. In each embodiment of the conductive layer 13 of the optoelectronic foil 10, the oxide layer 131 , 133 may preferably have a thickness in the range between 15 and 150 nm.

In one embodiment, the oxide layer 131 , 133 may take the form of a monolayer and consist of one type of oxide, from the group of oxides listed above, for example ZnO. In another embodiment, the oxide layer may take the form of a monolayer and consist of more than one material, for example the oxide layer 131 , 133, in the form of a monolayer may be made of ZnO doped with Al. In yet another embodiment, the oxide layer 131 , 133 may consist of at least two different oxides and may take the form of a multilayer comprising, within one oxide layer 131 , 133, at least two sublayers, wherein each sublayer is made of a different oxide material comprising at least one oxide. For example, the oxide layer 131 , 133 may consist of two sublayers stacked one on the other within one oxide layer 131 , 133, wherein one sublayer is made of ZnO and the other sublayer is made of AZO or IZTO doped with Al.

Depending on the intended use and the required parameters, the optoelectronic foil may comprise at least two oxide layers 131 , 133, wherein one oxide layer takes the form of a monolayer and another oxide layer takes the form of a multilayer comprising at least two sublayers made of different oxide materials. Moreover, in each embodiment of the conductive layer 13 comprising one or more than one oxide layers, the metal layer 132 is made of at least one metal selected from the group consisting of: Al, Ti, Ni, Cr, Au, Mg, Ta, Ge, Ag, Cu, Zr, Pt and W. For each embodiment of the conductive layer 13 of the optoelectronic foil 10, the metal layer 132 may preferably have a thickness in the range between 2 and 20 nm.

Depending on the target utility parameters of the optoelectronic foil, the foil 10 may have only one oxide layer 131 , 133 being a multilayer or a monolayer, and only one metal layer 132 within the conductive layer 13. Furthermore, in another embodiment, the conductive layer 13 may comprise, as schematically shown in Fig. 1 , two oxide layers 131 , 133, each of which may be a multi- or monolayer, and one metal layer 132 separating the two oxide layers. In another embodiment, the conductive layer 13 may have three oxide layers and two metal layers stacked within the conductive layer one alternately on the other, so that each of the metal layers separates the two adjacent oxide layers. In yet another embodiment, the conductive layer may have n oxide layers 131 , 133, each of which may be a multi- or monolayer, and n-1 metal layers stacked one on the other, so that each metal layer 132 separates two adjacent oxide layers 132, 133 forming a sandwich structure, where n is any number selected from the set of natural numbers. For example, n may be 2, 3, 4, 5, 6 or 7. For example, n may be up to 33, or n may be more than 33.

Fig. 2 schematically shows a manufacturing method of the optoelectronic foil.

A substrate material 11 is prepared in order to produce the optoelectronic foil in step 21. The preparation process involves thorough cleaning and activation of the selected substrate surface. The cleaning and activation process of step 21 is implemented using at least one technique selected from the group consisting of plasma treatment, corona discharge treatment, carbon dioxide treatment, cleaning with solvents such as acetone, isopropanol, water, or mixtures of acetone and water or a mixture of isopropanol and water, as well as surface treatment with ultraviolet (UV) radiation and ozone.

Then, in step 22, a barrier layer 12 is deposited onto the cleaned and activated surface of the substrate 11.

Depending on the structure of the barrier layer 12, step 22 may include one or more steps. For example, in order to form a barrier layer having a monolayer structure and made of at least one type of material, for example AI2O3, or AI2O3 doped with T1O2, in step 22 the barrier layer may be deposited in one step. However, in order to form a barrier layer with a multilayer structure comprising at least two sublayers made of different materials, the deposition step 22 may comprise several sub-steps, each involving depositing one sublayer onto the barrier layer 12. For example, to form a barrier layer comprising two sublayers, the deposition in step 22 is implemented so that a sublayer of one material is deposited in the first step, and then a sublayer of another material selected from the material group for the barrier layer 12 listed above is deposited. The processes of depositing the barrier layer 12 having both the structure of a multilayer and monolayer may be implemented using at least one known deposition technique selected from the group consisting of: atomic layer deposition (ALD) technique, magnetron sputtering technique, electron-beam sputtering technique and thermal evaporation technique.

Then, in step 23, a conductive layer 13 is deposited onto the barrier layer having a multi- or monolayer structure, wherein each of the sublayers of the conductive layer 13, that is at least one oxide layer 131 , 132 and at least one metal layer 132, is deposited onto the barrier layer 12 individually, in order to obtain the appropriate functionality and architecture of the conductive layer 13, e.g. a sandwich architecture. Each of the sublayers 131 , 132, 133 of the conductive layer can be deposited using various deposition methods also known from the art, selected from the group consisting of: atomic layer deposition (ALD) technique, magnetron sputtering, electron-beam sputtering technique and thermal evaporation technique.

For example, the conductive layer 13 having the architecture, as shown in Fig. 1 , comprising two oxide layers 131 , 133 and a metal layer 132 between the oxide layers, is deposited in step 23 so that in the first step, the first oxide layer 131 is deposited directly onto the surface of the barrier layer 12, then a metal layer 132 is deposited onto the first oxide layer, and then a second oxide layer 33 is deposited onto the metal layer 132. Each of the sub-layers 131 , 132, 133 may be deposited using the same or different deposition techniques.

Furthermore, depending on the target structure of the oxide layers 131 , 133, each of which may take the form of a monolayer or a multilayer, the oxide layer 131 , 133 may be deposited in step 23 in single step or several steps, each of which may be implemented using one technique as well as different deposition techniques. For example, for an oxide layer 131 , 132 having a monolayer structure made of an oxide material containing one type of oxide, for example: AI2O3, or an oxide material containing two types of oxides, for example AI2O3 doped with T1O2, the oxide layer 131 , 133 may be deposited in single step 23. Now, in order to form the oxide layer 131 , 133 having a multilayer structure consisting of at least two sublayers stacked one on the other, the oxide layer may be deposited in several steps in step 23, each step including depositing one sublayer within the oxide layer 131 , 133.

The optoelectronic foil obtained combines barrier properties and an efficient conductive layer 13, which preferably may have the architecture of an electrode, depending on the materials used as the materials for oxide and metal layers 131 , 132, 133, respectively. In each embodiment of the foil 10, the conductive layer 13 is integrated with an flexible substrate 1 1 , 12 having barrier properties.

The barrier layer of the optoelectronic foil has water vapor permeability rates (WVTR) ranging between 10 ^"3 and 10 ^"6 g/m ² per day and has stable barrier properties, including high hydrophobicity and UV radiation resistance, which improves the lifespan of the conductive layer of the foil according to the present invention.

Moreover, the optoelectronic foil is flexible and is characterised by relatively high transparency, while the conductive layer of the foil has good conductivity and is an alternative to the single, thicker conductive ITO (indium tin oxide) layer known in the prior art that is relatively brittle, has limited conductivity and is expensive.

Example 1

The optoelectronic foil according to one embodiment of the present invention is schematically shown as a cross-section in Fig. 1. The optoelectronic foil comprises a substrate 1 1 , which in this embodiment is made of a plastic, namely polyethylene terephthalate (PET). The top surface of substrate 1 1 was cleaned and activated using oxygen plasma treatment. Then, a single barrier layer 12 made of AIOx with a thickness of 300 nm, which is an amorphous layer, was deposited onto the top surface of substrate 1 1 thus prepared in the reactive magnetron sputtering process. Next, a conductive layer 13 was deposited onto the barrier layer 12 in the reactive magnetron sputtering process, comprising the first oxide layer 131 made of ITO with a thickness of 20 nm, a metal layer 132 made of Ag with a thickness of 9 nm and a second oxide layer 133 made of ITO with a thickness of 20 nm. The optoelectronic foil thus obtained was subjected to tests involving a measurement of surface resistance by means of a four-point probe, a WVTR permeability measurement by means of a calcium test (measurement conditions RH=40%, T = 25°C) and measurement of light transmission in the visible spectrum using a UV-Vis spectrophotometer. The tests conducted yielded a surface resistance of the conductive layer 13 of 12 Ω/D, a WVTR permeability rate of 10 ^"3 g/m ² per day and light transmission in the visible spectrum in the range of 70-78%. The use of a three-layer electrode structure (conductive layer 13), where the two oxide layers 131 , 133 are separated by a thin metal layer 132, provided high flexibility to the conductive layer 13 (due to the presence of the metal layer 12), and, as a result, to the entire optoelectronic foil, together with high conductivity are ensured, as demonstrated in the tests described above.

Example 2

The optoelectronic foil according to another embodiment of the present invention is schematically shown as a cross-section in Fig. 3. The optoelectronic foil comprises a substrate 11 , which in this embodiment is made of a plastic, namely polyethylene terephthalate (PET). The top surface of substrate 1 1 was cleaned and activated using oxygen plasma treatment. Then, a barrier layer 12 in the form of an AIOx layer 121 with a thickness of 100 nm and a TiOx layer 122 with a thickness of 150 nm, which constitute amorphous layers, were deposited onto the top surface of substrate 1 1 thus prepared in the reactive magnetron sputtering process. Next, a conductive layer 13 was deposited onto the barrier layer 12 in the reactive magnetron sputtering process, containing the first oxide layer 131 made of ITO with a thickness of 20 nm, a metal layer 132 made of Ag with a thickness of 9 nm and a second oxide layer 33 made of ITO with a thickness of 20 nm. The optoelectronic foil thus obtained was subjected to tests involving a measurement of surface resistance by means of a four-point probe, a WVTR perpieability measurement by means of a calcium test (measurement conditions RH=40%, T = 25°C) and measurement of light transmission in the visible spectrum using a UV-Vis spectrophotometer. The tests conducted yielded a surface resistance of the conductive layer 13 of 12 Ω/D, a WVTR permeability rate of less than 5 ^* 10 ^"4 g/m ² per day and light transmission in the visible spectrum in the range of 67-80%.