阅读说明：本技术 透明的多层组件和制造方法 (Transparent multilayer component and method of manufacture ) 是由 M·艾肯舍伊特 A·米特纳希特 T·施蒂格利茨 玛丽·T·阿尔特 于 2020-03-05 设计创作，主要内容包括：本发明涉及一种透明的多层组件(100),其例如用于制造太阳能电池或有机发光二极管(OLED),并且还涉及一种相应的制造方法。本发明还涉及具有这种透明的多层组件的太阳能电池和OLED。尤其地,透明的多层组件根据本发明包括具有聚合物材料的透明的载体结构(104)和具有导电氧化物的导电透明层(110),其中作为附着力增强措施在载体结构与导电透明层之间布置碳化硅层(108)。(The invention relates to a transparent multilayer component (100), for example for producing solar cells or organic light-emitting diodes (OLEDs), and to a corresponding production method. The invention also relates to solar cells and OLEDs having such transparent multilayer assemblies. In particular, the transparent multilayer component according to the invention comprises a transparent carrier structure (104) comprising a polymer material and a conductive transparent layer (110) comprising a conductive oxide, wherein a silicon carbide layer (108) is arranged between the carrier structure and the conductive transparent layer as an adhesion-promoting measure.)

1. A transparent multi-layer assembly (100) comprising:

a transparent carrier structure (104) with a polymer material,

a conductive transparent layer (110) having a conductive oxide,

wherein a silicon carbide layer (108) is arranged between the carrier structure (104) and the electrically conductive transparent layer (110) as an adhesion enhancing measure.

2. The transparent multilayer assembly according to claim 1, wherein the polymer material of the carrier structure (104) comprises polyimide PI, polyethylene terephthalate PET, polyethylene PE, polycarbonate PC, polyvinyl chloride PVC, polyamide PA, polytetrafluoroethylene PTFE, polymethyl methacrylate PMMA, polyetheretherketone PEEK, polysulfone PSU, parylene, polydimethylsiloxane PDMS and/or polypropylene PP.

3. The transparent multilayer assembly according to claim 1 or 2, wherein the conductive oxide comprises Indium Tin Oxide (ITO), Fluorine Tin Oxide (FTO), Aluminum Zinc Oxide (AZO), and/or Antimony Tin Oxide (ATO).

4. Transparent multilayer assembly according to any one of the preceding claims, wherein the silicon carbide layer (108) has a thickness of 10 to 100nm, preferably a thickness of about 50 nm.

5. The transparent multilayer assembly according to one of the preceding claims, wherein the electrically conductive transparent layer (110) is structured to constitute at least one electrode.

6. Transparent multilayer assembly according to one of the preceding claims, wherein a transparent cover layer (112) is further provided, which cover layer has a polymer material and at least partially covers the electrically conductive transparent layer (110).

7. Transparent multilayer assembly according to claim 6, wherein a second silicon carbide layer and/or a bilayer of silicon carbide layer and diamond-like carbon (DLC) layer (109) is arranged as adhesion enhancing means between the cover layer (112) and the electrically conductive transparent layer (110).

8. A method for manufacturing a transparent multilayer assembly (100), wherein the method comprises the steps of:

providing a transparent carrier structure (104) with a polymer material,

applying a silicon carbide layer (108) onto the carrier structure (104),

applying a conductive transparent layer (110) with a conductive oxide onto the silicon carbide layer (108) such that the silicon carbide layer (108) constitutes an adhesion enhancing measure between the carrier structure (104) and the conductive transparent layer (110).

9. The method according to claim 8, wherein the conductive transparent layer (110) is structured by means of a lithographic process.

10. Method according to claim 8 or 9, wherein the silicon carbide layer (108) is deposited on the carrier structure in a PECVD method, and/or wherein the electrically conductive transparent layer (110) is deposited on the silicon carbide layer (108) by means of reactive cathode sputtering.

11. The method according to any one of claims 8 to 10, wherein a transparent cover layer (112) is also applied, the cover layer having a polymer material and at least partially covering the electrically conductive transparent layer (110).

12. Method according to claim 11, wherein a second silicon carbide layer and a DLC layer (109) are deposited as adhesion enhancing means between the cover layer (112) and the electrically conductive transparent layer (110).

13. Method according to claim 11 or 12, wherein in the etching step contact openings (114) are introduced in the cover layer (112), through which contact openings a conductive transparent layer (110) can be contacted.

14. A solar cell (300, 400) having an absorbing layer (316, 416) and a transparent multilayer assembly according to any one of claims 1 to 7, wherein the electrically conductive transparent layer is electrically and optically connected with the absorbing layer.

15. An organic light emitting diode, OLED, (500) having a cathode (526), an emissive layer (516) and an anode (508), wherein the OLED has a transparent multilayer assembly according to any one of claims 1 to 7, and wherein the electrically conductive transparent layer constitutes the anode (508) of the OLED (500).

Technical Field

The invention relates to a transparent multilayer component, for example for producing solar cells or organic light-emitting diodes (OLEDs), and also to a corresponding production method. The invention also relates to solar cells and OLEDs having such transparent multilayer assemblies.

Background

For example, transparent electrodes are a major component of flexible optoelectronic applications, such as displays, imaging units and sensors. Here, the high-conductivity electrode is preferable for keeping the resistance low. In particular, for so-called wearable devices, i.e. body-mountable electronic devices or implantable components, high demands are made on flexibility, reliability and long-term stability.

Thin layers of transparent metals and semiconductors (so-called TCOs, transparent conductive oxides) are of particular importance in the solar industry and in screen development. Such TCOs are disclosed, for example, In publications "transparent conductive In" by N.Al-Dahudi and M.A. Aeger₂O₃Comparative study (c): sn (ITO) coating made using sol and nanoparticle suspensions (composite coating of transparent conductive In)₂O₃Sn (ITO) coatings using a sol and a nanoparticle coating), "Thin Solid Films (Thin Solid Films)," Vol.502, No.1-2, p.193 and 197, 2006, "and H.Liu, V.Avrutin, N.Izymskaya,and H.The publication "Transparent conductive oxides for electrode applications in light emitting and absorbing devices" (Superlatics and microstrusts, Vol. 48, No.5, p. 458-.

A material frequently used for new development is semiconductor ITO (Indium Tin oxide), the electrical properties of which can be adjusted in a targeted manner by doping (see, for example, b.t. minimi, "current state of the art for transparent conductive oxide Films for Indium Tin Oxide (ITO) substitutes" (Present state of the art), Thin Solid Films (Thin Solid Films), volume 516, No.17, page 5822-5828, 2008).

However, the mechanical properties of ITO are problematic, especially because it is prone to cracking due to its brittle fracture properties. In order to still integrate ITO into different production processes and to maintain its integrity there, ITO is mostly deposited on solid materials (e.g. glass or metal), as described in the following articles: h.k.lin, s.m.chiu, t.p.cho and j.c.huang "Improved bending fatigue properties of flexible PET/ITO films with thin metal glass interlayers (Improved bending fatigue property of flexible PET/ITO film with thin metal glass interlayer)", mate.lett., volume 113, page 182-185, 2013; s.k.park, j.i.han, d.g.moon and w.k.kim "Mechanical Stability of Externally Deformed Indium Tin Oxide Films on Polymer Substrates" (Mechanical Stability of external Deformed Indium-Tin-Oxide Films on Polymer Substrates) ", jpn.j.appl.phys., volume 42, No.1, No.2A, page 623. 629, 2003; "Stress-corrosion cracking of indium tin oxide coated polyethylene terephthalate for flexible photovoltaic devices" (Stress-corrosion cracking of indium tin oxide coated polyethylene terephthalate), Thin Solid Films (Thin Solid Films), Vol.517, No.8, p.2590-2595, 2009; sim, e.h.kim, j.park and m.lee, "Highly enhanced mechanical stability of indium tin oxide films with thin aluminum buffer layers deposited on plastic substrates with a thin Al buffer layer" surf.coat.technol., volume 204, No.3, page 309-; D. effect of "cyclic deformation of indium tin oxide film on polyethylene terephthalate substrate" of influence of impurities on conductive properties of indium tin oxide film on polyethylene terephthalate substrate "of p.tran, h.i.lu and c.k.lin, surf.coat.technique, vol 283, p 298-.

Recent advances in the electronics industry have been directed to flexible substrates made of polymers to enable the formation of variable and more complex structures with conductive films (abbolden). In particular, the following problems arise in the known construction.

In the production process, the known ITO layers have to be deposited and structured on a solid support material. Subsequent steps do not allow any thermal or mechanical stress to be introduced into the film, as such stress may create cracks and defects in the brittle film. However, for example, for very good conductivity, a thermal treatment of the TCO film (between 200 ℃ and 800 ℃) is essential (cf. N.Al-Dahudi and M.A. Aegerter "transparent conductive In₂O₃Comparative study (c): sn (ITO) coating made using sol and nanoparticle suspensions (composite coating of transparent conductive In)₂O₃Sn (ITO) coatings using a sol and a nanoparticle suspension), "Thin Solid Films (Thin Solid Films)," Vol.502, No.1-2, p.193 and 197, 2006 ".

Therefore, the light-transmissive and flexible coating and/or encapsulation of the ITO layer can only be carried out to a limited extent and thus a long service life cannot be guaranteed. The current methods are not perfect in the application field of mechanically alternating loads or high humidity, since only protective layers that are deposited and annealed at room temperature can be achieved (e.g. parylene, as described in "ultra flexible Transparent Oxide/Metal/Oxide stacked electrodes with Low Sheet Resistance for Electrophysiological Measurements" (eng), ACS printed materials & interfaces, volume 9, No.40, page 34744 and 34750, 2017, silicon or the like "in y. In this case, these layers place very special requirements on cleaning and downstream development processes.

In summary, the currently available multilayer components with thin, light-transmitting, electrically conductive or semiconductive layers have the disadvantage that subsequent coating or processing of the layers, which requires annealing at elevated temperatures, cannot be carried out. Thus, TCO is always one of the last process steps or has to be coated with a polymer deposited at low temperatures close to room temperature. Parylene is currently the only flexible polymeric material that can be deposited at room temperature using CVD methods (chemical vapor deposition), other CVD depositions do not yield flexible layers.

The TCO and ITO layers have to be deposited directly on glass or other solid supports, which does not allow mechanical flexibility.

In order to produce sufficient adhesion between the TCO and the flexible carrier polymer, it is also known to insert a thin metal layer, for example aluminum, silver, titanium or platinum, as an adhesion-enhancing measure (haftvermitler). However, this solution has the disadvantage that on the one hand the electrical properties are strongly influenced. Furthermore, if the metal layer is arranged below the TCO, the entire multilayer structure is no longer sufficiently optically transparent.

Disclosure of Invention

There is therefore a need for an optically transparent multilayer component which overcomes the disadvantages of the known solutions and is safe and reliable here, but can nevertheless be manufactured in a cost-effective manner.

This object is achieved by the subject matter of the independent claims. Advantageous embodiments of the invention are the subject matter of the dependent claims.

The invention is based here on the idea of using a thin layer of silicon carbide as an adhesion-enhancing measure between the flexible, light-transmitting carrier polymer and the electrically conductive, transparent layer. The inventors of the present invention were able to demonstrate that such SiC adhesion enhancement measures have a very small influence on the electrical and semiconductor properties of the TCO film, but here have both an optimum bonding property for the carbon chemistry of the polymer (kohlenstoff chemical) on the one hand and an optimum bonding property for the oxide structure of the TCO film on the other hand. Thus, silicon carbide has an excellent adhesion to polymers based on the carbon component and, on the other hand, forms a very good adhesion to TCO semiconductors based on the silicon component.

In particular, the transparent multilayer component according to the invention comprises a transparent carrier structure with a polymer material and a conductive transparent layer with a conductive oxide, wherein a silicon carbide layer is arranged between the carrier structure and the conductive transparent layer as an adhesion-promoting measure.

According to an advantageous embodiment of the transparent multilayer assembly, the polymer material of the carrier structure comprises polyimide PI, polyethylene terephthalate PET, polyethylene PE, polycarbonate PC, polyvinyl chloride PVC, polyamide PA, polytetrafluoroethylene PTFE, polymethyl methacrylate PMMA, polyetheretherketone PEEK, polysulfone PSU, parylene, polydimethylsiloxane PDMS and/or polypropylene PP. Polyimides are particularly inert and chemically stable here.

According to the present invention, the conductive oxide may include, for example, indium tin oxide ITO, fluorine tin oxide FTO, aluminum zinc oxide AZO, and/or antimony tin oxide ATO.

In order to be sufficiently light-transmissive for transparent multilayer components for visible light, the silicon carbide layer according to an advantageous development of the invention has a thickness of 10nm to 100nm, preferably a thickness of about 50 nm.

According to an advantageous development of the invention, the electrically conductive transparent layer is structured to form at least one electrode. Here, the at least one electrode may include a single electrode and an array composed of a plurality of electrodes. Advantageously, the finely structured electrodes are also reliably attached to the carrier structure.

In order to electrically insulate the electrically conductive transparent layer and/or to prevent chemical and mechanical loads, it may also be advantageous to provide a transparent cover layer which has a polymer material and at least partially covers the electrically conductive transparent layer.

Here, a second silicon carbide layer may optionally be arranged between the cover layer and the conductive transparent layer as an adhesion enhancing measure to improve the adhesion of the cover layer on the conductive transparent layer.

The invention also relates to a method for manufacturing a transparent conductive structure. The method comprises the following steps:

a transparent support structure is provided having a polymeric material,

a silicon carbide layer is applied to the carrier structure,

a conductive transparent layer with a conductive oxide is applied to the silicon carbide layer, such that the silicon carbide layer is configured as an adhesion-promoting measure between the carrier structure and the conductive transparent layer.

As already mentioned, in this way it is possible to produce transparent multilayer components in a cost-effective and simple manner, the individual layers of which are reliably and firmly connected to one another, wherein the multilayer components furthermore have a high mechanical flexibility.

In accordance with an advantageous embodiment of the method according to the present invention, the conductive transparent layer is structured by means of a lithographic process. Photolithography is a well-established process suitable for batch production with high precision and repeatability.

Advantageously, the silicon carbide layer is deposited on the carrier structure in a so-called PECVD method (plasma enhanced chemical vapor deposition). PECVD is a process in which thin films of different materials can be deposited onto a substrate using lower temperatures than standard CVD (chemical vapor deposition) methods. In the case of the PECVD method, deposition is caused by supplying a reaction gas between parallel electrodes, i.e., a ground electrode and an RF electrode. The capacitive coupling between the electrodes excites the reactant gases into a plasma which in turn causes the desired chemical reaction. Thereby, the reaction product is deposited on the substrate. The substrate disposed on the ground electrode is typically heated to a temperature of 250 ℃ to 350 ℃. In contrast, common CVD processes typically require 600 to 800 ℃. The inventors of the present invention are even able to achieve temperatures of 100 ℃ to 120 ℃ when performing SiC deposition, so that the photoresist is not damaged and thus lift-off methods and photo-structuring are possible.

According to an advantageous development of the method according to the invention, the electrically conductive transparent layer is deposited on the silicon carbide layer by means of reactive cathode sputtering. This method is also known as "reactive sputtering" and refers to a deposition method in which atoms are liberated from a solid (target) by bombardment with energetic ions, mainly inert gas ions, and are converted into the gas phase, wherein one or more reactive gases, such as oxygen or nitrogen, are added to an inert working gas, such as argon. The gas reacts with the sputtered layer atoms at the target, in the vacuum chamber or at the substrate and forms new species. The resulting reaction products are then deposited at the substrate surface.

In order to protect the conductive transparent layer, it is advantageously also possible to apply a transparent cover layer which has a polymer material and at least partially covers the conductive transparent layer.

Here, a second silicon carbide layer may be deposited between the cover layer and the conductive transparent layer as an adhesion enhancing measure to improve the adhesion of the cover layer on the conductive transparent layer. Preferably, an additional layer made of Diamond-Like Carbon (english: Diamond-Like-Carbon DLC), hereinafter referred to as DLC layer, is applied onto this silicon carbide layer in order to further improve the connection to a centrifugally coated liquid precursor (Vorstufe) of the polymer material when, for example, PI is used as polymer material for the cover layer.

In accordance with an advantageous development of the method according to the invention, contact openings can be introduced into the cover layer in the etching step, through which contact openings the conductive transparent layer can be contacted.

The invention also relates to a photovoltaic cell, hereinafter also referred to as solar cell, having an absorber layer and a transparent multilayer assembly according to the invention, wherein the electrically conductive transparent layer is electrically and optically connected to the absorber layer.

Such as H.Liu, V.Avrutin, N.Izyumskaya,and H.The article "Transparent conductive oxides for electrode applications in light emitting and absorbing devices" and "solar cells" describe in detail in volume 48, phase 5, page 458 and 484, 2010, the photovoltaic effect that solar cells convert incident light directly into electric current. Electron-hole pairs are generated by photons of light and are separated at the interface of two materials having different conductivity polarities. Various solar cell types are associated with conductive oxides. Furthermore, there can be classified in principle into thick-film and thin-film silicon solar cells, thin-film cells with single or multiple barrier layers, dye-sensitized solar cells, organic/polymer cells, and high-efficiency group III-V semiconductor-based solar cells with multiple barrier layers.

TCO is used as a transparent electrode in many types of thin film solar cells, such as silicon thin film solar cells, CdTe thin film solar cells, and Copper Indium Gallium Selenide (CIGS) thin film solar cells. The carrier concentration in the TCO must be as low as possible here to prevent undesired free carrier absorption in the infrared range, while the carrier mobility should be as high as possible to produce a sufficiently high conductivity.

In addition, thin film silicon cells have the advantage of being cost effective. Various photovoltaic technologies are based on thin films of silicon, for example on hydrogenated amorphous silicon (a-Si: H) with a quasi-direct band gap of 1.8eV, hydrogenated microcrystalline silicon (μ c-Si: H) with an indirect band gap of 1.1eV, a combination of these two forms on glass (microcrystalline silicon) and Polycrystalline Silicon (PSG).

The first three mentioned techniques use TCO as front and/or back electrode. According to the invention, silicon carbide is used as an adhesion-promoting means between the TCO layer and the corresponding carrier material. For example, such cells may be constructed according to the "Superstrate" principle, in which light passes through the carrier material into the active interior region. For such solar cells, the production process starts at the front side of the cell, which faces the light during operation, and proceeds toward the rear side. First, a TCO front contact layer is deposited on a transparent substrate layer, followed by amorphous and/or microcrystalline silicon and a TCO or metal back contact layer. Thus, the TCO front contact layer must be strong enough to withstand all subsequent layer deposition and processing steps without damage. In the known arrangements, the substrate layer is mostly made of glass. However, the use of a polymer layer according to the invention makes the solar cell flexible as well.

Finally, the invention also relates to an organic light-emitting diode OLED having a cathode, an emission layer and an anode, wherein the OLED has a transparent multilayer assembly according to the invention and wherein the electrically conductive transparent layer constitutes the anode of the OLED.

The following terms and definitions are used below.

In connection with the present invention, the term "flexible" means that the layer or the substrate is bendable and in particular can be deformed within certain limits without breaking.

The term "electrically conductive" is understood hereinafter to mean that a material is capable of conducting an electric current and is suitable for constructing an electrode. Thus, in addition to the conductivity exhibited by, for example, a metal, the conductivity of a semiconductor material is also intended to be included within the scope of the present invention.

Within the scope of the present invention, the terms "transparent" and "light-transmitting" shall denote a high light transmission for a specific wavelength of light, in particular in the visible range. However, it is clear to the person skilled in the art that the principles of the invention can also be applied in connection with radiation transparency in the infrared range.

Drawings

For a better understanding of the invention, it is explained in more detail with reference to the embodiments shown in the following figures. Here, the same components have the same reference numerals and the same component names. Furthermore, some features or combinations of features in the different embodiments shown and described may in themselves represent independent, inventive or solutions according to the invention. In the drawings:

FIGS. 1-6 show schematic diagrams of a manufacturing process of a transparent multilayer assembly according to a first embodiment of the invention;

FIGS. 7-13 show schematic diagrams of a manufacturing process of a transparent multilayer assembly according to a second embodiment of the invention;

FIG. 14 shows a graph of wavelength dependent light transmittance of different layers;

fig. 15 shows a schematic view of a first embodiment of a solar cell according to the invention;

fig. 16 shows a schematic view of a second embodiment of a solar cell according to the invention;

fig. 17 shows a schematic view of an advantageous embodiment of an OLED according to the invention.

Detailed Description

In the present invention, a transparent multilayer structure according to a first embodiment of the invention and its production are explained in detail with reference to the drawings and here, in particular, first to fig. 1 to 6. It should be noted that in all the figures the dimensional proportions and in particular the layer thickness proportions are not shown to the correct scale.

Fig. 1 schematically shows a silicon wafer 102 as a starting material, which is coated with a transparent carrier layer 104, for example a polyimide layer, and a photoresist 106. The silicon wafer 102 is used as a substrate only during the manufacture of the multilayer component 100 according to the invention in microsystem technology and will subsequently be removed. As is well known, the photoresist is structured in the exposure and structuring steps of the photolithographic technique such that the Polyimide (PI)104 is exposed in the areas where the subsequent TCO structure (e.g. ITO) is to be constructed (fig. 2).

According to the invention, in a next step a continuous silicon carbide layer 108 is first applied.

The silicon carbide layer 108 is preferably applied here by means of PECVD deposition. The silicon carbide layer 108 may have a thickness of 50nm, for example. Within this thickness range, but also significantly above, the silicon carbide is transparent to most wavelengths of interest. As already mentioned, PECVD (plasma enhanced chemical vapor deposition) refers to a process in which thin films of different materials can be deposited onto a substrate using lower temperatures than standard CVD (chemical vapor deposition) methods. In the case of the PECVD method, deposition is caused by supplying a reaction gas between parallel electrodes, i.e., a ground electrode and an RF electrode. The capacitive coupling between the electrodes excites the reactant gases into a plasma which in turn causes the desired chemical reaction. Thus, the reaction product, in this case SiC, is deposited on the substrate. The substrate disposed on the grounded electrode is typically heated to a temperature of 100 ℃ to 120 ℃ to ensure the integrity of the standard photoresist.

Due to their particular chemical and physical properties, silicon carbide forms a particularly tight bond with the underlying polymer layer, e.g., polyimide.

A transparent electrical semiconductor TCO layer 110 is next applied onto the silicon carbide layer 108. This state is shown in fig. 3. According to the present invention, the conductive oxide may include, for example, indium tin oxide ITO, fluorine tin oxide FTO, aluminum zinc oxide AZO, and/or antimony tin oxide ATO.

Such an ITO layer 110 may be deposited, for example, by means of reactive cathode sputtering. As previously mentioned, reactive cathode sputtering refers to a deposition process in which atoms are liberated from a solid (target material) by bombardment with energetic ions (mainly inert gas ions) and converted into the gas phase, wherein one or more reactive gases (e.g. oxygen or nitrogen) are added to an inert working gas (e.g. argon). The gas reacts with the sputtered layer atoms at the target, in the vacuum chamber or at the substrate and forms new species. The resulting reaction product, in the present case ITO, is then deposited at the substrate surface.

The silicon carbide layer is also able to form a strong bond with the ITO layer 110 due to the silicon component in the silicon carbide 108. The silicon carbide layer 108 thus forms an adhesion-enhancing means between the transparent polymer material (polyimide) 104 and the conductive material TCO, for example ITO 110.

In the next step, the adhesion promoter 108 and the TCO 110 are removed at all undesired places by stripping of the photoresist 106. As shown in fig. 4, only the structured TCO layer 110 remains attached to the base 104 by the adhesion enhancing means 108.

As shown in fig. 5, an additional polyimide layer may optionally be deposited as a cap layer 112 on the structured TCO layer 110. Of course, any other transparent polymer layer is also suitable as the cover layer 112. In the example shown, the carrier layer 104 and the cover layer 112 are composed of the same material. This need not be the case, however, and different materials may of course be used. For example, the following materials are contemplated for the cover layer 112 and the carrier layer 104: polyimide PI, polyethylene terephthalate PET, polyethylene PE, polycarbonate PC, polyvinyl chloride PVC, polyamide PA, polytetrafluoroethylene PTFE, polymethyl methacrylate PMMA, polyetheretherketone PEEK, polysulfone PSU, parylene, polydimethylsiloxane PDMS and/or polypropylene PP. Polyimides are particularly inert and chemically stable here.

The cover layer 112 serves for electrical insulation, but also for protection against chemical and mechanical environmental influences. The cover layer 112 may be a polyimide layer that is spun coated in the form of a liquid precursor and then heat treated to be hardened. As is known, a relatively high temperature, for example 450 °, is required for 10 minutes for this purpose. It should be noted that the attachment of the TCO film 110 on the carrier layer 104 is not affected by this requirement. The provision of the silicon carbide adhesion-promoting means according to the invention therefore allows the transparent conductive layers, after being applied to their carrier, to be subjected to further process steps which also involve higher temperatures. In particular, the transparent conductive layer can be embedded in a polymer, so that a transparent, flexible structure can be realized which is protected against the outside and is electrically insulating.

In order to be able to make electrical contact with the TCO layer 110 from the outside, the contact surfaces and/or the active structures are exposed through the openings 114 in the cap layer 112, for example by means of a dry etching step. Furthermore, the transparent flexible carrier layer 104 is separated from the silicon substrate 102. This can be done by an etching step as well. Finally (not shown in the figures) a separation of the individual components can be carried out, which are processed together as a batch as long as they are arranged on the silicon wafer 102.

Fig. 6 shows the completed transparent multilayer structure 100 with the schematically shown openings 114.

The production of a transparent multilayer assembly is described below according to another advantageous embodiment with reference to fig. 7 to 13.

The manufacturing steps shown in fig. 7 to 10 correspond to those in fig. 1 to 4, and thus the description will not be repeated.

As schematically shown in fig. 11, according to another embodiment, another adhesion promoter layer 109 is provided between the cap layer 112 and the underlying TCO layer 110. The adhesion-promoting means layer 109 may consist on the one hand of a further silicon carbide layer corresponding to the silicon carbide layer 108. However, experimental studies can show that the adhesion between the polymers of the cap layer deposited on the TCO film is different from the adhesion between the TCO films deposited on the polymer substrate. In particular, by applying a diamond-like carbon (DLC) layer in addition to another silicon carbide layer prior to depositing the polymer overlayer, a still further improved adhesion of the overlayer 112 on the TCO may be achieved. For example, the DLC layer is applied in a low temperature process, PECVD deposition at up to 100 ℃. Preferably, such additional DLC layer has a thickness of about 10 nm. In this way, an optimum adhesion of the polymer cover layer can be achieved. Thus, instead of directly covering the TCO layer 110 with the cap layer 112 as shown in FIG. 5, a double layer of SiC-DLC is also provided between the TCO layer 110 and the cap layer 112 as an adhesion promoter layer 109.

As shown in fig. 12, similar to fig. 5, another polyimide layer may optionally be deposited as a cap layer 112 on the structured TCO layer 110. The cover layer 112 serves for electrical insulation, but also for protection against chemical and mechanical environmental influences.

To enable electrical contact to the TCO layer 110 from the outside, the contact surfaces and/or the active structures are exposed through openings 114 in the cap layer 112, for example by means of a dry etching step. The adhesion promoter layer 109 is also opened here. Furthermore, the transparent flexible carrier layer 104 is separated from the silicon substrate 102. This can be done by an etching step as well. Finally (not shown in the figures) it is also possible to carry out a division of the individual components, which are processed together as a batch as long as they are arranged on the silicon wafer 102.

Fig. 13 shows the completed transparent multilayer structure 100 with the schematically shown openings 114.

Fig. 14 shows the light transmittance (in%) as a function of wavelength (in nm) for different materials provided in the transparent multilayer structure 100 compared to the glass layer required as a basis for measuring the light transmittance. Each curve shows the mean and associated standard deviation of the measurements. Here, the curve 201 indicates the light transmittance of glass, the curve 202 indicates the light transmittance of a 5 μm thick PI layer on a glass substrate, the curve 203 indicates the light transmittance of a 5 μm PI and a 300nm thick ITO layer on a glass substrate, and the curve 204 indicates the light transmittance of a 5 μm PI and a 600nm thick ITO layer on a glass substrate. Here, a SiC adhesion promoter layer is arranged between the PI substrate and the ITO layer.

As can be seen from fig. 14, the transmittance of the glass to visible to near-infrared light (curve 201) has an almost constant value of 91%, while about 80% of visible light greater than 470nm penetrates the PI layer (curve 202). The multilayer structure with the ITO layer exhibits a maximum light transmission in the range of 600nm, wherein the light transmission is significantly dependent on the layer thickness of the ITO layer (curves 203 and 204).

With reference to fig. 15 to 17, subsequent application examples of the transparent multilayer structure according to the invention are shown, in which the manufacturing process proceeds from bottom to top in a manner similar to the steps of fig. 1 to 6, respectively.

Fig. 15 shows a first technical application example of the transparent multilayer structure according to the present invention. In this schematic cross-sectional view a so-called microcrystalline solar cell 300 with hydrogenated amorphous silicon and microcrystalline silicon (a-Si: H/. mu.c-Si: H) as the working layer 316 is shown. As is known in this regard and is described, for example, in h.liu, v.avrutin, n.izyumskaya,and H.The article "Transparent conductive oxides for electrode applications in light emitting and absorbing devices" Superlatices and Microstructures, Vol.48, No.5, p.458 and 484, 2010, as described in,in the known solar cells, a glass substrate ("superstrate") is used on the light incidence side, which does not allow any mechanical flexibility. In contrast, the solar cell 300 according to the invention has a flexible transparent polymer carrier material 304 as a superstrate on the light incidence side. The TCO front electrode layer 310 is connected with the polymer carrier material 304 via the SiC adhesion promoter layer 308. Thus, SiC 308 enables a flexible and transparent front side that prevents corrosion of TCO layer 310.

An a-Si: H/. mu.c-Si: H layer is provided as the working layer 316 (also referred to as an absorption layer). This photovoltaic working layer 316 is followed by another TCO layer 318, which serves as a back contact. The metal layer 320 is used for reflection, as a diffusion barrier, and for improving conductivity. The other polymer layer 312 serves as an encapsulation cover layer.

Light 324 incident through the transparent carrier layer 304 is reflected and scattered multiple times due to the different refractive indices of the silicon or TCO layers 310, 316, 318 and in this way "trapped" in the silicon absorption layer 316, as it is shown in fig. 15. In this way, the thickness of the absorber layer 316 can be kept relatively small, which saves costs and increases the stability of the solar cell 300.

Advantageously, the entire solar cell 300 may be bendable, so that it may be rolled up in the unused state or may be adapted to different base profiles, for example.

As another technical application example of the transparent multilayer structure according to the present invention, a solar cell 400 with a CdTe (cadmium telluride) or CIGS (copper indium gallium selenide) absorber layer 416 is shown in fig. 16. In general, all current thin-film solar cells with the associated layers can be transferred to a flexible substrate according to the invention. Even organic solar cells with photoactive layers can be stabilized in this way.

According to the invention, the solar cell 400 has a flexible transparent polymer carrier material 404 on the light incidence side 424. The TCO front electrode layer 410 is connected to the polymer carrier material 404 via the SiC adhesion promoter layer 408. Thus, the SiC adhesion promoter layer 408 enables a flexible and transparent front side that prevents corrosion of the TCO layer 410. The working layer 416 is made of CdTe or CIGS absorber layer. As is known in this regard and is described, for example, in h.liu, v.avrutin, n.izyumskaya,and H.The article "Transparent conductive oxides for electrode applications in light emitting and absorbing devices" supra and microstresses, volume 48, No.5, page 458-.

In the case of CIGS solar cells, the absorber layer contains a CdS layer and a back side metallization structure in addition to the original CIGS absorber material. However, it is clear to the person skilled in the art that the principle according to the invention is compatible with any other layer sequence required, which can also be applied on the absorption layer 416 if necessary.

In general, all current thin-film solar cells with the associated layers can be transferred to a flexible substrate according to the invention. Even organic solar cells with photoactive layers can be stabilized in this way.

As another technical application example of the transparent multilayer assembly according to the present invention, an Organic Light Emitting Diode (OLED)500 is shown in fig. 17.

The OLED 500 has an organic working layer 516 between two electrodes, a metal cathode 526 and a transparent TCO anode 510. Typical thicknesses of organic films are about 100nm to 200 nm. Two organic materials are generally used here: long chain polymers or small molecules. If a voltage is applied between the anode and cathode, the cathode 526 injects electrons into the membrane 516. At the same time, holes (positive charges) are injected into the organic material 106 from the transparent anode 510 having a high work function. In the electric field, positive and negative charges migrate through the organic film 516. When the positive and negative charges recombine, the positive and negative charges form an excited state. If the charges and charges are annihilated, a photon is emitted and light 524 is generated.

According to the invention, the TCO layer 510 is connected to the transparent polymer layer 504 via the silicon carbide layer 508. The polymer cover layer 512 encloses the layer sequence of the OLED 500. In this way, the structural element can be completely encapsulated to protect against external influences. Furthermore, the OLED 500 is completely flexible, since glass carriers can be dispensed with.

In summary, the invention sets silicon carbide as a transparent adhesion enhancement measure between the polymer and the TCO, and is particularly suitable for the application of flexible films in the fields of liquid crystal screens, organic light emitting diodes, touch screens, switchable glass, thin film solar cells, photovoltaics, display technology, lighting technology, automotive technology, architectural glass, electrophysiological electrodes, pH sensors and antibody detectors.

This makes possible successful non-hermetic encapsulation of the TCO layer, especially for long-term stable use in aqueous media (or humid environments). Thereby providing a thermally and mechanically stable light transmitting layer for the above applications.

List of reference numerals

100 multilayer assembly

102 silicon

104. 304, 404, 504 transparent carrier structures; polyimide, polyimide resin composition and polyimide resin composition

106 photoresist

108. 308, 408, 508 silicon carbide

109 second adhesion promoter layer

110. 310, 410, 510 conductive transparent layers; TCO; ITO (indium tin oxide)

112. 312, 512 cover layer

114 opening for exposing TCO layer

201-204 transmittance curve

300. 400 solar cell

316. 416, 516 working layer

318 second TCO layer

320 metal layer

324. 424, 524 light

500 OLED

526 cathode.