A transparent photovoltaic device and a method of manufacturing the same

Abstract

A transparent photovoltaic (PV) device includes a semi-transparent substrate 120 and at least one transparent photovoltaic (PV) cell 100, the PV cell 100 including a stack 110 disposed on the substrate 120, the stack 110 including a front electrode layer 112, a back electrode layer 113, and a perovskite photoactive layer 111 between the anode layer and the cathode layer. The back electrode layer 113 includes carbon, wherein the stack 110 includes a laser fabricated light-transmitting aperture 130 extending at least through the back electrode layer 113 and the perovskite photoactive layer 111, wherein the light-transmitting aperture 130 is completely surrounded by the stack 110 that facilitates power conversion, such that the stack 110 of the single PV cell is electrically continuous.

Description

Technical Field

[0001] This disclosure relates to a transparent photovoltaic device and a method for manufacturing the same. Background Technology

[0002] Thin-film perovskite photovoltaic (PV) devices are very attractive due to their high absorption coefficient, high power conversion efficiency, low weight, and high production speed.

[0003] The ideal characteristic of such devices is translucency or transparency, which involves the ever-increasing energy consumption. Translucent and transparent PV devices, especially lightweight, preferably flexible PV devices, are suitable for application on windows and other transparent surfaces. Therefore, these PV devices can not only cover opaque surfaces (such as roofs or walls), but also take the form of glass walls of buildings, window and body films, as well as housings for cellular phones, tablets, laptops, and other electronic devices.

[0004] The translucency / transparency of perovskite PV devices is known to be achieved through three different methods. The first method involves using translucent materials to achieve this translucency. The second method involves using opaque materials such as metals for the individual layers of the PV device, followed by partial removal of the opaque material to create a viewing aperture that allows light to pass through. This removal is typically accomplished through mechanical scrubbing or laser ablation. The third method involves depositing a metal gate on a conductive polymer layer to achieve transparency. This deposition is achieved using various printing techniques, such as inkjet printing and screen printing.

[0005] PV devices obtained by the first method are usually called semi-transparent PV devices, while PV devices obtained by the second and third methods are called transparent PV devices.

[0006] While laser ablation can achieve the transparency required for PV devices, it removes a portion of the working material of the PV cell, thus reducing the overall efficiency of the PV device. Nevertheless, for substantially high-efficiency PV devices (e.g., those with a perovskite photoactive layer), this drawback becomes negligible. Furthermore, the efficiency of the resulting transparent device can be controlled by increasing or decreasing the size of the ablation region, and the desired characteristics of the PV device can be achieved by striking a proper balance between the desired transparency and the volume of ablated material, depending on the specific application requirements.

[0007] However, significant drawbacks remain in the field of transparent PV devices, which are related to the ablation method itself, thus limiting the transparency achieved by the characteristics of the resulting viewing aperture. Furthermore, depending on the materials used, some transparent PV devices exhibit high red transparency, which restricts their application range.

[0008] Unlike the latter, transparent perovskite PV devices are characterized by the transmission of neutral-colored light. Furthermore, these perovskite PV devices exhibit high power conversion efficiency, making them suitable for applications in the fabrication of transparent PV devices with viewing apertures.

[0009] The scientific publication "Transparent, Neutral-Colored, High-Efficiency Perovskite Thin-Film Solar Cell Module," by L. Rakocevic et al., *Journal of Materials Chemistry C* (2018, DOI: 10.1039 / C7TC05863B), describes a transparent perovskite PV device in which the light-transmitting aperture is obtained through laser ablation and mechanical scrubbing. This device constitutes a perovskite solar PV cell module with a planar nip structure. The module consists of monolithically interconnected PV cells. The method for fabricating the PV device involves forming an opaque device and subsequently applying patterning (referred to as P4) in a strip design. The P4 patterning method involves removing four layers: a bottom (back) contact layer, a hole transport layer, a perovskite photoactive layer, and an electron transport layer. However, patterning P4 does not remove the front contact layer, i.e., the electrodes directly disposed on a semi-transparent substrate. In one embodiment, P4 patterning is performed using picosecond laser ablation, and in a second embodiment, it is performed using a mechanical scrubbing method. The resulting strips are parallel to each other, forming an alternating design of opaque and transparent strips, where each opaque strip acts as a single module. Therefore, the resulting transparent aperture, to some extent, divides a PV cell into smaller strip-like structures with multiple electrical connections disposed on a semi-transparent front electrode layer. Consequently, the light-transmitting aperture of the device is not completely surrounded by the individual layers in the stack that facilitate power conversion (in particular, the P4 enclosure is inactive, considering the delamination of the top metal electrode during laser ablation). The publication also describes the disadvantages of both methods should laser patterning cause damage, i.e., delamination of the functional layers of the PV device.

[0010] Furthermore, patent publication US9257592 describes a photovoltaic device comprising multiple light-transmitting holes. This device includes a substrate, a first electrode layer, a photoconductive layer, and an outermost second electrode layer (made of metal). The first light-transmitting hole is formed on the second electrode layer and further extends along the depth direction into the photoconductive layer to form multiple second light-transmitting holes corresponding to the first light-transmitting hole. The projection area of ​​each second light-transmitting hole is smaller than the projection area of ​​the corresponding first light-transmitting hole. The difference in area size between the first and second light-transmitting holes can eliminate short circuits. Nevertheless, the proposed method involves a multi-step laser method for separately forming the first and second light-transmitting holes, which is complex. This multi-step operation is necessary because if laser cutting is performed through all layers in a single step, the second electrode metal layer may melt due to thermal effects, causing conductive layer bridging and thus creating short circuits between conductive layers. Therefore, the second electrode metal layer is removed in the first step (forming a larger area hole), and another layer is removed in the second step (forming a smaller area hole). Furthermore, the light-transmitting aperture of the device is completely surrounded by the layers in the stack that facilitate power conversion (in particular, considering the lack of a top electrode around the aperture, which is inactive).

[0011] WO 2019 / 070977 A1 describes a large-scale method for manufacturing PV modules using perovskite photoactive materials; however, it does not explicitly mention the transparency of the modules. According to this disclosure, cells can be separated by processing them on a substrate (preferably glass) using laser or mechanical scrubbing (patterning P1 to P3) with the corresponding layers. The back electrode can be made of carbon, but this does not offer any particular advantage, as carbon is only one of many materials that can be used.

[0012] CN 109 273 608 A describes a transparent PV cell comprising holes formed by laser in a tangential manner, extending at least through a back electrode layer made of metal instead of carbon. These holes are formed in a P3 patterning step and are not completely surrounded by the layers of a single PV cell.

[0013] CN 108 574 048 A describes a PV module comprising a perovskite photoactive layer and a back electrode made of carbon paste. This document introduces some advantages of using carbon electrodes, such as low cost, good stability, and simple processing. Furthermore, it discloses how to avoid short circuits by separating the positive and negative electrodes of the cell itself using an insulating layer. However, the PV module according to this disclosure does not include pores within a single cell to provide light transmittance for the cell. This disclosure only shows pores between adjacent cells, which are not completely surrounded by the stack consisting of the individual layers of each cell.

[0014] US 4795500 discloses a PV module comprising a plurality of light-transmitting holes formed in a stack of each PV cell, the holes being completely surrounded by the stack, and a back electrode made of metal, the holes being formed using a laser. However, the PV module according to US4795500 has drawbacks, namely, short circuits and leakage current problems due to the high-temperature laser cutting process.

[0015] CN 101 232 058 A describes a method for fabricating a transparent PV component. Furthermore, it provides two types of holes, one extending along the Y direction and the other along the X direction, thus offering a solution to the aforementioned shortcomings of US 4795500:

[0016] US 2007 / 251566 A1 describes a light-emitting device including a transparent light-emitting layer disposed on the light-incident surface of a photovoltaic cell. The device includes a translucent photovoltaic cell and a light source disposed on the back surface side of the photovoltaic cell. The arrangement of the device allows light emitted from the light source to pass through the photovoltaic cell and exit to the front surface side of the photovoltaic cell. The device has a photoelectric conversion layer made of silicon, rather than a perovskite photoactive layer. Furthermore, the device has openings for transmitting light from the inside of the module to the outside (because the light (LED) is generated by the module), and there is no mention of using carbon as a back electrode layer.

[0017] US 2006 / 112987 A1 describes a solar cell module that includes laser-fabricated light-transmitting holes, which are completely surrounded by a stack and formed at least in the back electrode layer. The module does not have a perovskite photoactive layer or a carbon back electrode layer.

[0018] US 2019 / 198256 A1 describes a solar cell comprising a perovskite photoactive layer and a diffusion shield layer located between the photoelectric conversion layer and the anode, the diffusion shield layer comprising at least one selected from the group consisting of: metal oxides, metal nitrides, metal oxynitrides, each comprising a metal from Groups 6 to 15 of the periodic table; and carbon. The cathode is transparent, and the anode may be made of metal. US 2019 / 198256 A1 does not mention a carbon electrode, nor does it mention multiple light-transmitting holes in each solar cell stack of the module.

[0019] CN 106 356 456 B describes a solar cell based on a perovskite heterojunction. The solar cell includes a substrate, a transparent electrode, an electron transport layer, a metal framework layer, a perovskite absorber layer, a hole transport layer, and a reverse (back) electrode. CN 106 356 456 B neither describes nor suggests forming multiple light-transmitting holes in the stack of each solar cell in the module to achieve light transmittance for a single solar cell.

[0020] As can be seen from the above disclosure, there is a need to further develop methods for manufacturing transparent photovoltaic (PV) devices with laser-fabricated light-transmitting apertures, simplifying the manufacturing process, and eliminating short-circuiting and delamination effects in the working layer of transparent PV devices, thereby obtaining transparent PV devices with improved operating characteristics. Furthermore, there is a need to provide a lightweight PV device exhibiting flexibility to expand its potential applications. Summary of the Invention

[0021] This invention provides a transparent photovoltaic (PV) device, comprising a semi-transparent substrate 120 and at least one transparent photovoltaic (PV) cell 100. The PV cell 100 includes a stack 110 disposed on the substrate 120, the stack 110 including a front electrode layer 112, a back electrode layer 113, and a perovskite photoactive layer 111 located between the anode layer and the cathode layer. The back electrode layer 113 comprises carbon, and the stack 110 includes a laser-formed light-transmitting aperture 130 extending at least through the back electrode layer 113 and the perovskite photoactive layer 111, wherein the light-transmitting aperture 130 is completely surrounded by the stack 110 that promotes power conversion, such that the stack 110 of the single PV cell is electrically continuous.

[0022] Preferably, the stack 110 further includes a front charge transport layer 112a and a back charge transport layer 113a, wherein the front charge transport layer 112a is disposed between the perovskite layer 111 and the front electrode layer 112, and the back charge transport layer 113a is disposed between the perovskite layer 111 and the carbon back electrode layer 113.

[0023] Preferably, the stack 110 further includes a front passivation layer 112b and / or a back passivation layer 113b, wherein the front passivation layer 112b is disposed between the perovskite layer 111 and the front charge transport layer 112a, and the back passivation layer 113b is disposed between the perovskite layer 111 and the back charge transport layer 113a.

[0024] Preferably, the back electrode layer 113 has a thickness of 10 nanometers to 1000 micrometers.

[0025] Preferably, the transparent PV device includes a plurality of transparent PV cells 100, each of the transparent PV cells 100 including a plurality of light-transmitting holes 130 formed by the laser, the light-transmitting holes 130 having a diameter of 1 μm. 2 Up to 1000cm 2 The area is such that the distance between two adjacent light-transmitting holes 130 is 1μm to 100cm.

[0026] Preferably, the transparent PV device comprises a nip structure PV cell.

[0027] Preferably, the stack 110 of the PV cell 100 adopts the following configuration: AZO / SnO2 / perovskite / PTAA / carbon.

[0028] Another aspect of this disclosure constitutes a method for manufacturing a transparent photovoltaic (PV) device including at least one transparent photovoltaic (PV) cell 110. The method includes the steps of: providing a semi-transparent substrate (120); forming a stack 110 of the PV cell 100 on the substrate, the stack including: a front electrode layer 112, a back electrode layer 113, and a perovskite photoactive layer (111) located between the front electrode layer 112 and the back electrode layer 113. The step of forming the stack 110 of the PV cell 100 includes forming the back electrode layer 113 from carbon. The method further includes the step of laser-patterning a light-transmitting aperture 130 in the stack 100 of the PV cell 100, wherein the aperture 130 extends at least through at least a portion of the carbon back electrode layer 113 and the perovskite photoactive layer 111, and is completely surrounded by the stack 110 that facilitates power conversion.

[0029] Preferably, each light-transmitting hole 130 is formed in a one-step laser processing P4.

[0030] Preferably, the light-transmitting hole 130 is formed using a nanosecond IR laser.

[0031] Preferably, a plurality of the light-transmitting holes 130 are formed in the stack 110 of each PV cell 100.

[0032] Preferably, the light-transmitting aperture 130 has a diameter of 1 μm. 2 Up to 1000cm 2 The area is such that the distance between two adjacent light-transmitting holes 130 is 1μm to 100cm.

[0033] Preferably, the step of forming the stack 110 further includes forming a front charge transport layer 112a between the perovskite layer 111 and the front electrode layer 112, and forming a back charge transport layer 113a between the perovskite layer 111 and the carbon back electrode layer 113.

[0034] Preferably, the step of forming the stack 110 further includes forming a front passivation layer 112b between the perovskite layer 111 and the front charge transport layer 112a and / or forming a back passivation layer 113b between the perovskite layer 111 and the back charge transport layer 113a.

[0035] Preferably, forming the carbon back electrode layer 113 includes the following steps: providing a carbon paste; forming a carbon layer as the top layer of the stack 110 of the PV cell; and drying the carbon layer in the stack 110 to obtain the carbon back electrode layer 113. Attached Figure Description

[0036] The purpose of this disclosure is illustrated by exemplary embodiments in the accompanying drawings, wherein:

[0037] Figure 1A A schematic representation of a cross-sectional view of the main components of the PV cell of the transparent PV device provided in this disclosure is shown;

[0038] Figure 1B and Figure 1C An overall view and two cross-sectional views of an embodiment of the transparent PV device provided in this disclosure are shown;

[0039] Figure 2A A schematic representation of a cross-sectional view of the main components of a PV cell in a transparent PV device according to another embodiment of the present disclosure is shown;

[0040] Figure 2B A schematic representation of a cross-sectional view of the main components of a PV cell in a transparent PV device according to another embodiment of the present disclosure is shown;

[0041] Figure 3 A photograph of a perovskite photovoltaic device obtained by the method described in accordance with this disclosure is shown;

[0042] Figures 4A to 4C SEM images of the light-transmitting aperture formed according to the method described in this disclosure are shown;

[0043] Figure 5A A diagram showing transmission measurements of a transparent PV device is presented;

[0044] Figure 5B A diagram showing the JV characteristics of a transparent PV device in both forward and reverse scanning is presented.

[0045] Figure 6 A cross-sectional FIB-SEM image of the structure is shown. Detailed Implementation

[0046] The developed method for manufacturing transparent photovoltaic (PV) devices enables the production of PV devices with improved quality transparent apertures. Specifically, the obtained apertures are free of metallic impurities and have a regular shape, avoiding significant delamination effects. Due to these characteristics, no short circuits were observed in the resulting PV devices. Furthermore, the developed method can be simplified, allowing the formation of transparent apertures using cheaper nanosecond lasers instead of the expensive picosecond or femtosecond lasers used in known methods.

[0047] Although nanosecond lasers are characterized by a much larger heat-affected zone than picosecond lasers, the relatively large heat-affected zone of nanosecond lasers does not cause problems in the resulting structure due to the structure of the PV device according to the invention (with a carbon back electrode), where the carbon electrode will burn and will not come into contact with the other electrode (bridging).

[0048] Furthermore, the PV devices described in this disclosure are characterized by improved transparency and the ability to be manufactured in the form of lightweight, flexible PV modules.

[0049] Furthermore, based on the final structure and materials used in the PV devices described in this disclosure, the PV devices can be used in a variety of applications, such as photovoltaic devices, electroluminescent devices such as light-emitting diodes (LEDs), building-integrated photovoltaics (BIPV) for facades, windows, etc., photovoltaic vehicle integration for car windows or public transportation, as well as Internet of Things (IoT) devices, autonomous sensors, Industry 4.0 devices, smart homes / cities, portable electronic devices, e-readers, smartphones, smart furniture, and other electronic devices.

[0050] The resulting effect is achieved through a complex set of characteristics, including the selection of carbon materials for the back contact electrode and the application of laser ablation technology to create light-transmitting holes to achieve transparency in PV devices. Figures 1A to 1C The transparent PV device provided in this disclosure is illustrated schematically.

[0051] The transparent PV device includes a translucent substrate 120 that allows light to pass through. Preferably, the substrate 120 is a flexible sheet, and more preferably a plastic foil, such as polyethylene terephthalate (PET), which allows the substrate 120 to be easily and reversibly deformed, thereby providing flexibility to the final product. The foil, especially PET foil, can also have the advantage of exhibiting limited vapor transfer, thus preventing the working layer of the PV device from contacting water and gases, thereby limiting the degradation of PV device characteristics.

[0052] Nevertheless, depending on the requirements, the substrate 120 can be made of a thick and / or durable and / or rigid material, such as a glass plate. Furthermore, the substrate can be made of a transparent laminated material, such as laminated glass. According to this disclosure, various materials can be used as the substrate 120 as long as it is light-transmitting.

[0053] PV devices also include at least one photovoltaic cell 100. Figure 1A A schematic cross-sectional view of the main parts of a PV cell is shown.

[0054] The PV cell includes a stack 110, comprising: a front electrode layer 112 made of a translucent material capable of transmitting light to a perovskite layer 111; an opaque back electrode layer 113 made of carbon; and the perovskite layer 111 located between the front electrode layer 112 and the back electrode layer 113. The perovskite layer 111 is the photoactive layer of the PV device. In the perovskite material, visible photons are absorbed and converted into a pair of charges, namely an electron-hole pair. These charges propagate to the back electrode layer 113 and the front electrode layer 112, respectively.

[0055] like Figure 2A As shown, preferably, the stack 110 of the PV cell further includes two charge transport layers 112a and 113a for transporting holes and electrons to the front electrode layer 112 and the back electrode layer 113, respectively, as is typically achieved in known perovskite PV cells.

[0056] Depending on the required operating characteristics and functional materials used in the PV cell 100, the stack 110 can have various structures. For example, the stack 110 of the PV cell 100 can have a planar or mesoscopic nip structure, wherein the back electrode layer 113 constitutes the cathode layer and the front electrode layer 112 constitutes the anode layer. Therefore, the charge transport layers 112a and 113a for carrying charge are respectively the electron transport layer 112a located between the perovskite layer 111 and the anode layer 112 and the hole transport layer 113a located between the perovskite layer 111 and the cathode layer 113.

[0057] In another embodiment, the stack 110 of the PV cell 100 may have a planar or mesoscopic pin structure, wherein the back electrode layer 113 constitutes the anode and the front electrode layer 112 constitutes the cathode. Therefore, the charge transport layers 112a and 113a for carrying charge are respectively the hole transport layer 112a located between the perovskite layer 111 and the cathode layer 112 and the electron transport layer 113a located between the perovskite layer 111 and the anode layer 113.

[0058] Because carbon has a deep work function (5-5.1 eV), it can be used as a hole transport layer and electrode. Therefore, the nip structure is suitable for using carbon as the top electrode for hole extraction.

[0059] Carbon is organic and does not react with ions migrating from the perovskite layer, thus its devices are more stable than those made of any metal electrode. It can be processed into solutions using conventional techniques such as sieving, troughing, and blade coating. Carbon is a commercially available, low-cost material.

[0060] Furthermore, P4 patterning can be performed in one step via a carbon back electrode and other layers (as described in detail below), because the laser beam ablates the material of the electrode and causes it to be completely removed (unlike prior art solutions with a metal back electrode, which can melt and therefore cannot be removed in one step along with other layers), thus eliminating the risk of contact (bridging) between the top and bottom electrodes. Alternatively, multi-step P4 patterning can be used if desired. Figure 2A As shown, it presents an embodiment of a PV device, wherein the substrate 120 may be in the form of PET foil, and the PV cell 100 may include a nip structure stack 110.

[0061] The stack 110 includes an opaque back electrode layer 113 and a translucent front electrode layer 112, wherein the opaque back electrode layer 113 is made of carbon and the translucent front electrode layer 112 is made of AZO (Al2O3-doped ZnO). However, other materials can be used as the front electrode layer 112 for use as the anode, among which non-limiting examples include indium-doped tin oxide (ITO), fluorine-doped tin oxide (FTO), or dielectric / metal / dielectric (DMD) structures, such as ITO / Ag / ITO. The stack 110 of the PC battery also includes tin dioxide (SnO2) and poly(triarylamine) (PTAA), wherein SnO2 serves as a charge carrier layer 112a for propagating electrons to the cathode 112, and PTAA serves as a charge transport layer 113a for propagating holes to the carbon-made anode 113. SnO2 can also be replaced with various other materials, such as TiO2. x ZnO, PCBM, or OXD-7. This also applies to PTAA materials, which can be replaced with, for example, nickel oxide (NiO). x Copper thiocyanate (I) (CuSCN), copper oxide (II) (CuO), molybdenum oxide (MoOx), poly(3,4-ethylenedioxythiophene) (PEDOT), poly(3-hexylthiophene-2,5-diyl) (P3HT), or spirodifluorene (N2,N2,N2′,N2′,N7,N7,N7′,N7′-octa-(4-methoxyphenyl)-9,9′-spirobis[9H-fluorene]-2,2′,7,7′-tetraamine).

[0062] For a nip device structure in which the carbon back electrode layer 113 is arranged as a cathode, another non-limiting example of a charge carrier layer can be used. For example, the charge carrier layer 113a used to propagate holes to the carbon cathode layer 113 can be selected from the group consisting of: NiOx, CuSCN, CuO, MoOx, PEDOT, P3HT, spirodifluorene, and poly(triarylamine) (PTAA).

[0063] However, for example, the positive charge transport layer 112a used to propagate electrons to the anode front layer 112 can be selected from the group consisting of: titanium oxide (TiO2) x ), zinc oxide (ZnO), methyl phenyl-C61-butyrate (PCBM) or 1,3-bis[2-(4-tert-butylphenyl)-1,3,4-oxadiazol-5-yl]benzene (OXD-7SnO) x ), Tin(II)(SnO) x ).

[0064] In another embodiment of the PV device according to this disclosure, the carbon back electrode layer 113 can be implemented as the anode. Until now, only nip structures of carbon have been reported. The inventors of this disclosure have discovered that pin devices with carbon as the top electrode can be fabricated by providing a buffer layer between the n-type layer and the carbon to achieve efficient electron transport.

[0065] In yet another embodiment of the invention, such as Figure 2B As shown, additionally, at least one of the front passivation layer 112b and / or the back passivation layer 113b can be incorporated into the photovoltaic device 100 located between the photoactive layer 111 and the charge transport layers 112a and 113a. The passivation layers 112b and 113b can reduce or suppress nonradiative recombination at the interface between the photoactive material 111 and the charge transport layers 112a and 113a. This can be achieved through ionic bonding, coordination materials, and transforming the surface into a region with a band gap wider than that of the photoactive material 111. The passivation layers 112b and 113b can be made of materials selected from the group consisting of Lewis acids and bases, anions and cations, zwitterions, semiconductors, and insulators. Some non-exhaustive examples include: perovskite materials with compositions different from the photoactive layer bulk; insulators (e.g., polymers such as poly(methyl methacrylate) (PMMA), small molecules such as copper bath (BCP), PCBM and its derivatives, self-assembled monolayers (SAMs), etc.); ionic materials such as NaCl and KI; and AlO₂. x (e.g., metal oxides such as Al2O3). The thickness of the passivation layers 112b and 113b can be selected as needed, which improves photoelectric performance; however, its presence does not significantly affect the process required to fabricate transparent devices via laser patterning.

[0066] Non-limiting examples of perovskite materials that can be used in pin and nip structures include three-dimensional ABX3-type perovskite structures composed of a BX6 octahedral network sharing corners, where the B atoms are divalent metal cations (typically Ge). 2 + Sn 2+ or Pb 2+ X is a monovalent anion (usually Cl-). - ,Br - I - A cation is selected to balance the total charge and can be Cs. + Or small molecules. Another type is two-dimensional perovskite, which can be divided into Ruddlesden-Popper and Dion-Jacobson types, with the following structure: R2A n-1 B n X 3n+1 R is a large organic cation. Phenylethylammonium (PEA) + ) and butylammonium (BA) + ) is the most widely used R cation.

[0067] The carbon back electrode layer 113 comprises carbon (and may also include inorganic additives to improve performance). The carbon layer can be flexible because a polymeric binder bonds the carbon black and conductive graphite flakes together. Furthermore, the layer is relatively thin, preferably about 20 micrometers. To form the carbon back electrode layer 113, the carbon material can be provided in the form of a paste. The carbon layer 113 can be formed by applying the carbon paste as a back contact deposition. The basic components of the paste are carbon black, graphite, a polymeric binder, and a solvent system compatible with perovskite.

[0068] For example, a carbon paste as mentioned in patent document CN104966548 can be used, which has the following solvent system: isopropanol, ethyl acetate, and chlorobenzene. Acrylic resin and ethyl cellulose are used as binders for the paste, flake graphite is used as a conductive filler, nano-carbon black powder is used as a catalyst, and ZrO2 or NiO is used as an inorganic additive.

[0069] Carbon paste can be deposited onto the device stack using a semi-automatic screen printing machine. The printing process can utilize a polyester screen with a mesh size of 156-250 lines / inch and a screen tension >25 N / cm. After deposition, these layers can be annealed using an infrared emitter to remove solvents and improve conductivity.

[0070] Figure 1B and Figure 1C A transparent PV device according to an embodiment of the present disclosure is shown, wherein Figure 1BA schematic top view of the device is shown. Figure 1C Two cross-sectional views of the PV device along lines AA and BB are schematically shown.

[0071] The PV device includes at least one PV cell 100, but preferably may include multiple PV cells 100. Figure 1B and Figure 1C A PV device comprising two PV cells 100 is shown. However, a PV device may include more than two PV cells 100. The number of PV cells 100 implemented in a PV device depends on engineering requirements, available area, and design considerations (losses due to sheet resistance).

[0072] At least one PV cell 100 of the PV device is transparent, and preferably, more than 50% of the PV cells 100 of the PV device is transparent, and even more preferably, all the PV cells 100 of the PV device are transparent.

[0073] Each transparent PV cell 100 of the PV device includes at least one light-transmitting hole 130, and preferably includes multiple light-transmitting holes 130, formed in the stack 110 of PV cells disposed on the substrate 120.

[0074] Figure 1B A non-limiting example of an array of light-transmitting holes 130 disposed within a PV cell 100 is shown.

[0075] The light-transmitting aperture 130 enables the transparency of the PV device. Therefore, the larger the area occupied by the light-transmitting aperture 130 (further referred to as the transparent area), the higher the transparency of the PV device.

[0076] The light-transmitting holes 130 within the stack 110 of the PV cell working layer can reduce the working area of ​​the PV cell. Therefore, depending on the specific requirements of the application and component design, the transparent area preferably constitutes 10% to 90% of the total area of ​​the corresponding PV cell. Thus, a suitable characteristic of PV devices is that they have visible transparency.

[0077] Preferably, the transparency area ratio is selected based on the required light transmission and the performance of the PV device, tailored to individual needs.

[0078] Preferably, the PV cells 100 are electrically connected to each other through a connection between the anode of one PV cell and the cathode of another PV cell.

[0079] Each light-transmitting aperture 130 is formed in one step by laser beam processing, allowing the laser beam to penetrate each layer in the stack 110, thus removing the material of the stack in a single operation. It has been found that the delamination effect at the edges of the apertures 130, present in prior art solutions, can be eliminated by using a carbon back electrode layer 113.

[0080] Furthermore, if all layers in the stack 110 are removed, removing the front electrode layer and the back electrode layer can improve the transparency of each formed light-transmitting hole 130 and even the entire PV device.

[0081] Because the optimized laser parameters (as shown in Table 1 below) enable layer removal without damaging the substrate, the substrate 120 is unaffected by the laser beam, while simultaneously forming the light-transmitting aperture 130. Using higher laser power would damage the substrate; using lower power would not completely remove the layer. Therefore, after laser processing, the substrate 120 remains continuous, thus forming a barrier protecting the interior of the PV device from environmental influences.

[0082] A method for manufacturing a transparent PV device includes: providing a translucent substrate 120, such as a plastic foil; and forming a stack 110 of the working layer of a PV cell 110 by means of successive deposition and laser patterning steps P1 to P4 as described below. For example, as Figure 1C As shown, the front electrode can be removed by laser patterning P1 to create individual cell regions. Depending on the material of the front electrode, various lasers can be used for P1 patterning; for example, infrared lasers are typically used for transparent conductive oxides (TCOs). After depositing a front charge transport layer 112a on the front electrode layer 112, a second laser patterning P2 may be performed. The front electrode layer 112 can be either an electron transport layer or a hole transport layer, depending on whether the PV cell structure is pin- or nip-based. Laser patterning P2 locally removes the charge carrier layer 112a. Typically, IR or other visible lasers can be used in P2 patterning.

[0083] Next, an opaque carbon back electrode layer 113 is deposited and a patterning step P3 is performed to define the boundaries of each cell or separate them into individual cells.

[0084] After the P3 patterning step is completed, the carbon layer forms the back electrode layer 113, and such devices only include opaque (non-transparent) PV cells due to the presence of a continuous carbon back electrode layer 113 that is itself opaque.

[0085] Next, the stack 110 is laser-patterned P4 to form at least one light-transmitting hole 130, preferably multiple light-transmitting holes 130, within the stack 110 of the working layer of the PV cell 100, such that the holes 130 extend at least through at least a portion of the back electrode layer 113 and the perovskite photoactive layer 111. This allows the PV cell to transmit light. Optionally, to further improve light transmittance, the holes 130 may extend through all layers in the stack 110 from the back electrode layer 113 to the front electrode layer 112.

[0086] In P4 patterning, the laser affects the stack 110 opposite the substrate 120.

[0087] Each light-transmitting aperture 130 is created in a one-step laser processing, such that the laser beam simultaneously penetrates each layer in the stack 110 of the PV cell, and these layers are removed along the depth of the aperture 130.

[0088] Therefore, the light-transmitting aperture 130 is completely surrounded by the layers in the stack 110 that facilitate power conversion (in other words, surrounded by the effective area of ​​the solar cell), that is, all layers are directly adjacent to the aperture 130 or adjacent to each other along the vertical wall of the aperture 130 (in contrast to the prior art, where the top layer in the stack is removed from the aperture wall or is layered).

[0089] Holes 130 are formed in a one-step laser patterning process P4. The cross-section of the holes 130 along their depth is substantially uniform (i.e., they form well holes with substantially straight sidewalls that taper slightly toward the bottom).

[0090] When forming the light-transmitting holes 130 that penetrate the stack 110, the front surface to the back surface of the stack 110 is formed in one step, thereby simplifying the method and shortening the production process. In P4 patterning, the laser beam does not affect the substrate. This is achieved by optimizing the laser parameters.

[0091] Furthermore, after the pores 130 are formed, at least some of the pores 130 may be filled with functionalized reagents, such as inks or pigments that can provide the color appearance of PV batteries.

[0092] The developed PV cell stack 110 structure provides the above-mentioned improvement for transparent PV devices, namely, realizing a carbon back electrode layer 113, which is naturally opaque, only becoming transparent when laser-processed due to the presence of a laser-made light-transmitting hole 130.

[0093] It is believed that the carbon material in the back electrode layer 113 will be completely oxidized and burned during laser treatment. Therefore, when the carbon material is removed by laser, the byproducts of the laser-carbon interaction will not contaminate the interior of the light-transmitting aperture 130. Unlike metallic materials typically used for opaque back electrode layers, it is estimated that carbon will not melt or evaporate when interacting with the laser beam, thus providing the desired effect. Therefore, according to this method, the light-transmitting aperture 130 does not include any unremoved material remaining in the back electrode layer 113, and this further eliminates short-circuit effects and delamination of the carbon layer (because the carbon layer does not melt).

[0094] The developed method has a further advantage, wherein transparency is achieved by forming a light-transmitting aperture 130 that penetrates the working layer of the PV cell. The PV device obtained by the method according to this disclosure can exhibit a variety of conductivity characteristics of the material used for the back electrode layer. Thicker layers reduce resistance and increase conductivity, but also increase material cost. An optimal value is defined through this fine balance to match device performance with appropriate cost. Conductive silver-copper pastes are also commercially available and can be screen-printed to form thick layers. However, they are preferably not subjected to P3, as this requires high power to remove micrometer-thick layers and may damage the bottom electrode. P4 laser processing for achieving transparency is also unsuitable, as it would melt together with the bottom electrode and cause a short circuit. In this research, thin metal electrodes in the 100 nm range are formed by an evaporation process, which is suitable for laser P3 removal to form devices with high geometry fill factor.

[0095] Furthermore, the implementation of carbon materials does not require the additional lateral conductive layer needed in known metal gate schemes.

[0096] Because the formed aperture 130 allows light to pass through the PV device, the perovskite layer used can be relatively thick, as the perovskite material does not form a light barrier in the developed structure. The thicker the perovskite active region, the more light is absorbed, resulting in a higher photocurrent.

[0097] Furthermore, since the carbon layer is implemented as the back electrode layer 113 instead of a metal layer, the formation of the light-transmitting aperture 130 can be accomplished using a cheaper standard laser. According to the developed method, more expensive picosecond or femtosecond lasers are not required, thus reducing the overall production cost.

[0098] For example, according to this method, an IR laser can be used in the P4 patterning step, and therefore, the same laser used in the patterning steps from P1 to P3.

[0099] The array of light-transmitting holes 130 can be arranged into various patterns according to individual needs. In addition, the array can also take various forms of aesthetic creation.

[0100] The light-transmitting aperture 130 can take various shapes that can be obtained by a laser beam. Nevertheless, preferably, the photoactive regions (i.e., the opaque regions of the stack 110 of each transparent PV cell) are electrically continuous. In other words, the photoactive (opaque) regions thus take the form of continuous paths extending between the light-transmitting apertures 130 to collect all the charge generated in the PV cell.

[0101] Preferably, the light-transmitting holes 130 are circular and uniformly distributed within the PV cell. Depending on the required transparency, the light-transmitting holes 130 can have various areas, and the area of ​​the light-transmitting holes 130 can vary within a single PV cell. Preferably, each light-transmitting hole 130 can have a size ranging from 1 μm. 2 Up to 1000cm 2 The area of ​​the laser is such that the distance between the two closest light-transmitting apertures 130 (depending on the laser resolution) ranges from 1 μm to 100 cm. Multiple laser points can be formed adjacent to each other or overlap each other.

[0102] On a macroscopic scale, the light-transmitting holes 130 with this area and spacing are substantially uniformly distributed within the given range, giving the user the impression that the entire PV device is transparent (semi-transparent). This is due to the selected size and spacing of the light-transmitting holes 130.

[0103] Therefore, transparent PV devices can be used to cover glass panels on buildings.

[0104] Example - Fabrication of transparent PV devices with nip PV cell structure.

[0105] Transparent PV devices were fabricated on a flexible PET substrate, wherein the front electrode layer was made of AZO (300 nm) from Eastman, and the PET and AZO were integrally formed into a foil. The remaining layers of the PV cell stack were deposited by spin coating in the following order: electron transport layer (SnO2), perovskite (as perovskite photoactive layer), and stoichiometric Cs. 0.05 (MA 0.17 FA 0.83 ) 0.95 Pb(I 0.83 Br 0.17 )3, where Cs is cesium, MA is methylammonium, FA is formamidinium, Pb is lead, I is iodine, Br is bromine, and PTAA (as a hole transport layer). For the back electrode layer, carbon paste from EMS (CI-2042) was coated and annealed for 5 minutes at approximately 80°C using a gas quenching method. The thickness of the carbon paste, measured by FIB-SEM, was 20 μm, providing a sheet resistance of approximately 20 Ω / sq. Subsequently, the formed device was laser-patterned (P4) using a 1064 nm Nd:YAG nanosecond laser from Rofin-PowerLine. Transparency was achieved by ablating transparent holes (dots) in a matrix pattern, each hole having a diameter of 200 μm and a spacing of 500 μm. Laser ablation was performed to avoid interference with the PET substrate. Table 1 below shows the parameters used for laser patterning.

[0106] Table 1 - Parameters used for laser patterning

[0107] Current 23A frequency 3000Hz speed 195mm / s Line width 100μm Pulse width 100μm Incubation method Two-way

[0108] Figure 3 An overview photograph of the obtained transparent PV device is shown, in which the formed apertures enable transparency. Next, SEM images are taken to study the details of the formed apertures. Figures 4A to 4C The SEM images shown were taken using a scanning electron microscope (SEM). The images reveal that the pores are regular circles with a diameter of 200 μm; there is no obvious layering effect.

[0109] In further research, cross-sectional focused ion beam scanning electron microscopy (FIB-SEM) images of the structure inside the light-transmitting aperture (130) showed (Image 1) that the stack (110) had been completely removed and (Image 2) that the stack (110) was in an active state.

[0110] Figure 6 Image 1 confirms that the laser pulse ablates all layers down to the substrate.

[0111] Subsequently, a JV reverse scan was performed on the obtained devices to evaluate their JV characteristics. For example... Figure 5B As shown, the results obtained confirm that the device is functioning normally and is capable of generating electricity.

[0112] In addition, transmission measurements were performed on the device, and the results are as follows: Figure 5A As shown. The results obtained confirm that the device allows light to pass through.

Claims

1. A transparent photovoltaic (PV) device, comprising a semi-transparent substrate (120) and at least one transparent photovoltaic (PV) cell (100), said PV cell (100) comprising a stack (110) disposed on the substrate (120), said stack (110) comprising: - Front electrode layer (112); - A carbon back electrode layer (113), wherein the front electrode layer and the back electrode layer constitute an anode layer and a cathode layer; - A perovskite photoactive layer (111) is located between the anode layer and the cathode layer. Its features are, The carbon back electrode layer (113) comprises carbon black, graphite, and polymer binder as basic components. The stack (110) of the (PV) cell (100) includes a laser-formed light-transmitting aperture (130) extending at least through the front electrode layer (112), the carbon back electrode layer (113), and the perovskite photoactive layer (111) of the (PV) cell. The light-transmitting aperture (130) is completely surrounded by the stack (110) that facilitates power conversion, such that the stack (110) of the (PV) cell is electrically continuous. Each light-transmitting hole (130) includes a hole wall that forms a substantially smooth surface and extends at least through the front electrode layer (112), the carbon back electrode layer (113), and the perovskite photoactive layer (111). The front electrode layer (112) and the carbon back electrode layer (113) do not contain perovskite.

2. The transparent photovoltaic (PV) device according to claim 1, wherein the semi-transparent substrate (120) is flexible.

3. The transparent photovoltaic (PV) device according to claim 1 or 2, wherein the stack (110) further comprises a front charge transport layer (112a) and a back charge transport layer (113a), wherein the front charge transport layer (112a) is disposed between the perovskite photoactive layer (111) and the front electrode layer (112), and the back charge transport layer (113a) is disposed between the perovskite photoactive layer (111) and the carbon back electrode layer (113).

4. The transparent photovoltaic (PV) device according to claim 3 further includes a front passivation layer (112b) and / or a back passivation layer (113b), wherein the front passivation layer (112b) is disposed between the perovskite photoactive layer (111) and the front charge transport layer (112a), and the back passivation layer (113b) is disposed between the perovskite photoactive layer (111) and the back charge transport layer (113a).

5. The transparent photovoltaic (PV) device according to claim 1, wherein the carbon back electrode layer (113) has a thickness of 10 nanometers to 1000 micrometers.

6. The transparent photovoltaic (PV) device according to claim 1, comprising a plurality of transparent (PV) cells (100), each of the transparent (PV) cells (100) comprising a plurality of laser-manufactured light-transmitting holes (130), the light-transmitting holes (130) having a diameter of 1µm. 2 Up to 1000cm 2 The area is such that the distance between two adjacent light-transmitting holes (130) is 1 μm to 100 cm.

7. The transparent photovoltaic (PV) device according to claim 1, wherein the PV cell has a nip structure.

8. The transparent photovoltaic (PV) device according to claim 7, wherein the stack (110) of the (PV) cell (100) adopts the following configuration: AZO / SnO2 / perovskite / PTAA / carbon.

9. A method for manufacturing a transparent photovoltaic (PV) device comprising at least one transparent photovoltaic (PV) cell (100), the method comprising the following steps: - Provide a semi-transparent substrate (120); - A stack (110) of the (PV) cell (100) is formed on the substrate (120), the stack (110) comprising: a front electrode layer (112); a carbon back electrode layer (113), wherein the front electrode layer and the back electrode layer constitute an anode layer and a cathode layer; and a perovskite photoactive layer (111) located between the front electrode layer (112) and the carbon back electrode layer (113). Its features are, The step of forming the stack (110) of the (PV) cell (100) includes forming the carbon back electrode layer (113) from a carbon paste, the basic components of which are carbon black, graphite, polymer binder, and a solvent system compatible with perovskite. The method further includes a step of laser patterning (P4) a light-transmitting aperture (130) in the stack (110) of the (PV) cell (100), wherein the aperture (130) extends at least through at least a portion of the carbon back electrode layer (113) and the perovskite photoactive layer (111), and is completely surrounded by the stack (110) that promotes power conversion, such that the stack (110) of the (PV) cell is electrically continuous. - Each of the light-transmitting holes (130) includes a hole wall that forms a substantially smooth surface and extends at least through the front electrode layer (112), the carbon back electrode layer (113), and the perovskite photoactive layer (111). -The front electrode layer (112) and the carbon back electrode layer (113) do not contain perovskite.

10. The method of claim 9, wherein each light-transmitting aperture (130) is formed in a one-step laser patterning (P4).

11. The method according to claim 9 or 10, wherein the light-transmitting aperture (130) is formed by using a nanosecond IR laser.

12. The method of claim 9, wherein a plurality of the light-transmitting holes (130) are formed in the stack (110) of each (PV) cell (100).

13. The method according to claim 9, wherein the light-transmitting aperture (130) has a diameter of 1 µm. 2 Up to 1000cm 2 The area is such that the distance between two adjacent light-transmitting holes (130) is 1µm to 100cm.

14. The method of claim 9, wherein the step of forming the stack (110) further comprises forming a front charge transport layer (112a) between the perovskite photoactive layer (111) and the front electrode layer (112), and forming a back charge transport layer (113a) between the perovskite photoactive layer (111) and the carbon back electrode layer (113).

15. The method of claim 14, wherein the step of forming the stack (110) further comprises forming a front passivation layer (112b) between the perovskite photoactive layer (111) and the front charge transport layer (112a) and / or forming a back passivation layer (113b) between the perovskite photoactive layer (111) and the back charge transport layer (113a).

16. The method of claim 9, wherein forming the carbon back electrode layer (113) comprises the following steps: - Provide carbon paste; - A carbon layer is formed as the top layer of the stack (110) of the (PV) cell; -Dry the carbon layer in the stack (110) to obtain the carbon back electrode layer (113).

Images