Semi-transparent photovoltaic device and method for manufacturing same

Abstract

[Solution] A semi-transparent photovoltaic device comprising a semi-transparent substrate 120 and at least one light-transmitting photovoltaic cell 100, the photovoltaic cell 100 comprising a stack 110 disposed on the substrate 120, the stack 110 comprising a front electrode layer 112, a back electrode layer 113, and a perovskite photoactive layer 111 between an anode layer and a cathode layer. A transparent photovoltaic device, wherein the semi-transparent substrate 120 comprises the light-transmitting photovoltaic cell 100. The back electrode layer 113 is made of carbon, and the stack 110 includes a laser-made semi-transparent aperture 130 that extends through at least the back electrode layer 113 and the perovskite photoactive layer 111, the semi-transparent aperture 130 being completely surrounded by the stack 110 of layers that contribute to power conversion.

Description

[Technical field]

[0001] SUMMARY The present disclosure relates to semi-translucent photovoltaic devices and methods for making same. [Background technology]

[0002] Thin-film perovskite-based photovoltaic devices (PV devices) are attractive due to their high absorption coefficient, high power conversion efficiency, light weight, and rapid manufacturability.

[0003] A desirable feature of these devices is their semi-transparency or translucency, which is associated with a constant increase in energy consumption. Translucent and semi-transparent photovoltaic devices, especially those that are lightweight and preferably flexible, are suitable for application on windows and other see-through surfaces. They can therefore be applied not only to opaque surfaces such as roofs and walls, but also to glass walls of buildings, stickers on car windows and bodies, and cases for electronic devices such as mobile phones, tablets, and laptops.

[0004] Translucency in perovskite photovoltaic devices is known to be achieved in three different ways. The first method is to provide the device with translucency by using a semi-transparent material. The second method is to use an opaque material such as a metal in each layer of the photovoltaic device, followed by partial removal of the opaque material to form see-through holes, thereby allowing light to pass through the device. Removal is usually achieved by mechanical scrubbing or laser ablation. The third method is to deposit a metal in a grid on a conductive polymer layer, which makes it semi-transparent. This deposition is done by various printing techniques, such as inkjet or screen.

[0005] Photovoltaic devices obtained by the first method above are generally called "semi-transparent", while those obtained by the second and third methods are called "translucent".

[0006] Laser ablation provides the necessary semi-transparent properties for photovoltaic devices, but it also removes some of the working material of the photovoltaic cell, reducing the overall efficiency of the photovoltaic device. However, in substantially more efficient photovoltaic devices, such as those having perovskite photoactive layers, this drawback becomes negligible. Furthermore, the efficiency of the resulting semi-transparent device can be controlled by increasing or decreasing the size of the ablated area, and the appropriate balance between the required semi-transparent and the volume of ablated material can be achieved to obtain the desired properties of the photovoltaic device depending on the needs of a particular application.

[0007] Nevertheless, important problems remain in the field of semi-transparent photovoltaic devices related to the ablation method itself, and therefore to the properties of the see-through apertures formed to provide transparency. In addition, some semi-transparent photovoltaic devices exhibit high red-colored transparency depending on the materials used, which limits their scope of application.

[0008] Differently, semi-transparent perovskite-based photovoltaic devices are characterized by neutral color semi-transparency (achromatic color transparency). Furthermore, perovskite-based photovoltaic devices exhibit high power conversion efficiency, so they can also be used in the field of semi-transparent photovoltaic devices with semi-transparent see-through openings (apertures).

[0009] In the scientific journal "Translucent, Color-neutral and Efficient Perovskite Thin Film Solar Modules L. Rakocevic, et al, J. Mater. Chem. C, 2018, DOI: 10.1039 / C7TC05863B" a semi-transparent perovskite photovoltaic device is described, in which the semi-transparent apertures are obtained by both laser ablation and mechanical scrubbing. The device consists of a planar nip-structured perovskite solar photovoltaic cell module. The module consists of monolithically interconnected photovoltaic cells. The fabrication method of the photovoltaic device consists of forming an opaque device and then applying an additional patterning (called P4) in a strip design. The P4 patterning method involves the removal of four layers: a bottom 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 electrode formed directly on the semi-transparent substrate. Patterning P4 is performed using picosecond laser ablation in one embodiment and mechanical scrubbing in a second embodiment. The resulting strips are parallel to each other and form an alternating design of opaque and transparent strips, each opaque strip acting as a single module. The semi-transparent aperture thus divides, to some extent, one photovoltaic cell into several small, electrically connected strip-like structures formed in the semi-transparent front electrode layer. Therefore, the semi-transparent aperture of the device is not completely surrounded by the stack of layers that contribute to the power conversion (especially in terms of the peeling of the top metal electrode during laser ablation, the periphery of P4 is inactive). This document describes the disadvantage of both methods, that laser patterning causes damage such as peeling of the functional layers of the photovoltaic device.

[0010] Furthermore, patent publication US9257592 describes a photovoltaic device consisting of a plurality of semi-transparent apertures. This device is composed of a substrate, a first electrode layer, a photoconductive layer, and a second electrode layer (made of metal) as the outermost layer. The first semi-transparent aperture is formed on the second electrode layer, while the aperture is further extended in the depth direction to the photoconductive layer to form a plurality of second semi-transparent apertures corresponding to the first semi-transparent apertures. The projected area of ​​each second semi-transparent aperture is smaller than the projected area of ​​the corresponding first semi-transparent aperture. The first and second semi-transparent apertures have different area sizes, so that short circuits can be prevented. However, this method requires a complicated multi-step laser method to separately form the first and second semi-transparent apertures. This is because if laser cutting were performed on all layers at once, the thermal effect would melt the second electrode metal layer, potentially bridging the conductive layers and causing a short circuit. Thus, in a first step the second electrode metal layer is removed (creating a large area hole) and in a second step further layers are removed (creating a smaller area hole). Furthermore, the semi-transparent aperture of the device is not completely surrounded by stack layers that contribute to power conversion (its periphery is inactive, especially considering that there is no top electrode around the aperture).

[0011] WO2019 / 070977A1 ​​describes a method for large-scale manufacturing of photovoltaic modules using perovskite photoactive materials, but does not explicitly mention the optical transparency of the modules. According to this disclosure, cells can be processed on a substrate (preferably glass) by using a laser or mechanical scribing of each layer (patternings P1-P3) to separate each cell. The back electrode may be made of carbon, but there is no particular advantage to using this material, as carbon is one of many possible materials.

[0012] CN109273608A describes a light-transmitting photovoltaic cell having a tangential laser-created aperture extending through at least the bottom electrode layer made of metal instead of carbon. These apertures are created in the P3 patterning step and are not completely surrounded by a single layer of photovoltaic cells.

[0013] CN108574048A describes a photovoltaic module including a perovskite photoactive layer and a bottom electrode made of carbon paste. The document lists the advantages of the carbon electrode, such as low cost, stability, and ease of processing. It also discloses a method of avoiding short circuits by isolating the positive and negative electrodes of the unit itself with an insulating layer. However, the photovoltaic module according to the disclosure does not constitute an aperture in a single cell provided for transmitting the light of the cell. Each cell is not completely surrounded by a stack of layers, and only the aperture between adjacent cells is shown.

[0014] US4795500 discloses a photovoltaic module in which a stack of photovoltaic cells is formed with a number of semi-transparent apertures, the apertures being completely surrounded by the stack, the back electrode being made of metal, and the apertures being formed using a laser. However, the photovoltaic module according to US 4,795,500 suffers from short circuit and leakage current problems due to the high temperature laser cutting process.

[0015] CN 101 232 058 A describes a method for making a light-transmitting photovoltaic module, and solves the above-mentioned shortcomings of US4795500 by providing two types of apertures, one extending in the Y direction and the other in the X direction.

[0016] US2007 / 251566A1 discloses a light-emitting device including a light-transmitting light-emitting layer disposed on the light-incident surface of a photovoltaic cell. The device is composed of a light-transmitting photovoltaic cell and a light source disposed on the back side of the photovoltaic cell. The device is disposed so that light emitted from the light source passes through the photovoltaic cell and is output to the front side of the photovoltaic cell. The device is provided with a silicon-based photoelectric conversion layer instead of a perovskite photoactive layer. Furthermore, an aperture is provided to transmit light (LED) from inside the module to the outside, and there is no mention of using carbon for the back electrode layer.

[0017] US 2006 / 112987 A1 describes a solar module that includes a laser-produced semi-transparent aperture completely surrounded by a laminate and produced in at least a back electrode layer, the module being free of a perovskite-type photoactive layer and a carbon back electrode layer.

[0018] US2019 / 198256A1 describes a solar cell comprising a perovskite photoactive layer, and a diffusion prevention layer between the photoelectric conversion layer and the anode, the diffusion prevention layer including at least one selected from the group consisting of metal oxides, metal nitrides, and metal oxynitrides each including a metal of Groups 6 to 15 of the periodic table; and carbon. The cathode may be semi-transparent, and the anode may be made of metal. US2019 / 198256A1 does not describe carbon electrodes or semi-transparent apertures formed in the stack of each solar cell of the module.

[0019] CN106356456B discloses a solar cell using a perovskite heterojunction. The solar cell is composed of a substrate, a transparent electrode, an electron transport layer, a metal skeleton layer, a perovskite absorption layer, a hole transport layer, and a counter electrode (back electrode). CN106356456B does not describe or suggest a plurality of semi-transparent apertures formed in the stack of each solar cell of the module to obtain semi-transparent properties of a single photovoltaic cell. Summary of the Invention [Problem to be solved by the invention]

[0020] From the above publications, it is desired to further develop a method for manufacturing a translucent photovoltaic device with a laser-made semi-translucent aperture, providing both a simplified manufacturing process and avoiding short-circuiting and peeling effects, and obtaining a translucent photovoltaic device with improved operating characteristics.Furthermore, it is desired to provide a photovoltaic device with light weight and flexibility to expand the range of applications. [Means for solving the problem]

[0021] The present invention relates to a semi-transparent photovoltaic device according to claim 1 and to a method for producing a semi-transparent photovoltaic device according to claim 9. Preferred embodiments are defined in the dependent claims. [Brief description of the drawings]

[0022] The objects of the present disclosure are illustrated in the drawings by way of exemplary embodiments, in which: [Figure 1A] FIG. 1A is a schematic diagram of a cross-sectional view showing the main elements of a photovoltaic cell of a semi-transparent photovoltaic device according to the present disclosure. [Figure 1B] FIG. 1B illustrates one embodiment of a semi-transparent photovoltaic device according to the present disclosure in an overall view and two cross-sectional views. [Figure 1C] FIG. 1C illustrates one embodiment of a semi-transparent photovoltaic device according to the present disclosure in an overall view and two cross-sectional views. [Figure 2A] FIG. 2A is a schematic diagram of a cross-sectional view showing the main elements of a photovoltaic cell of another embodiment of a semi-transparent photovoltaic device according to the present disclosure. [Figure 2B] FIG. 2B is a schematic diagram of a cross-sectional view showing the main elements of a photovoltaic cell of another embodiment of a semi-transparent photovoltaic device according to the present disclosure. [Diagram 3] FIG. 3 is a photograph showing a perovskite photoactive device obtained by a method according to the present disclosure. [Figure 4]4A-4C are SEM photographs of semi-transparent apertures formed according to the method of the present disclosure. [Figure 5A] FIG. 5A shows the transmittance measurement of a semi-transparent photovoltaic device. [Figure 5B] FIG. 5B shows the forward and reverse scan JV characteristics of a semi-transparent photovoltaic device. [Figure 6] FIG. 6 shows a cross-sectional FIB-SEM image of the structure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The developed method for producing semi-transparent photovoltaic devices allows to obtain photovoltaic devices with semi-transparent apertures of improved quality. In particular, apertures free of metal impurities, with regular shapes and less susceptible to delamination can be obtained. In particular, the obtained apertures are free of metal impurities, with regular shapes and not susceptible to significant delamination. Due to the above features, no short circuits are observed in the obtained photovoltaic devices. Furthermore, the developed method is simplified and can be achieved with the use of inexpensive nanosecond lasers for forming the semi-transparent apertures instead of expensive picosecond or femtosecond lasers used to form such apertures according to known solutions.

[0024] Nanosecond lasers are characterized by a much larger heat affected zone than picosecond lasers, but due to the structure of the photovoltaic device according to the present invention (having a carbon electrode on the back side), the carbon electrode burns and does not contact (bridge) with other electrodes, so the relatively large heat affected zone of the nanosecond laser does not cause problems in the structure formed.

[0025] Additionally, photovoltaic devices according to the present disclosure are characterized by improved optical transparency and can be fabricated in the form of lightweight, flexible photovoltaic (photovoltaic) modules.

[0026] Also, depending on its final structure and the materials used, the photovoltaic devices according to the present disclosure may be employed in various applications such as photovoltaic devices, electroluminescent devices such as LEDs (light emitting diodes), building integrated photovoltaics (BI photovoltaics) for facades, windows, etc., vehicular photovoltaics such as windows in cars and public transport, Internet of Things (loT) devices, autonomous sensors, Industry 4.0 devices, smart home / city, portable electronics, electronic devices such as e-readers, smartphones, smart furniture, etc.

[0027] This effect was achieved through a variety of ingenious measures, including the selection of the carbon material used for the rear contact electrode and the application of laser ablation technology to form a semi-transparent aperture that enhances the transparency of the photovoltaic element.

[0028] 1A-1C show schematic diagrams of a semi-transparent photovoltaic device according to the present disclosure.

[0029] The semi-translucent photovoltaic device consists of a translucent substrate 120 through which light can pass. Preferably, the substrate 120 is a flexible sheet, more preferably a plastic foil, for example made of PET (polyethylene terephthalate), so that the substrate 120 can be easily reversibly deformed, thus providing flexibility of the final product. Foils, especially PET foils, can be further advantageous as they limit the transmission of vapors and therefore protect the working layers of the photovoltaic device from exposure to water and gas, thereby inhibiting degradation of the photovoltaic device properties.

[0030] Nevertheless, depending on the needs, the substrate 120 may be in the form of a thick and / or durable and / or rigid material, such as a glass sheet. Additionally, the substrate may be in the form of a translucent laminate, such as laminated glass. In accordance with the present disclosure, various materials may be used as the substrate 120, so long as the substrate 120 allows light to pass therethrough.

[0031] The photovoltaic device further comprises at least one photovoltaic cell 100. Figure 1A shows a schematic cross-sectional view of the main parts of a photovoltaic cell.

[0032] The photovoltaic cell is composed of a stack 110 including a front electrode layer 112 made of a semi-transparent material that allows light to pass through to the perovskite layer 111, an opaque back electrode layer 113 made of carbon, and a perovskite layer 111 between the front electrode layer 112 and the back electrode layer 113. The perovskite layer 111 is the photoactive layer of the photovoltaic device. In the perovskite material, light photons are absorbed and converted into pairs of charges, called electron-hole pairs. These charges propagate to the back electrode layer 113 and the front electrode layer 112, respectively.

[0033] As shown in FIG. 2A, the photovoltaic cell layer stack 110 preferably further comprises two charge transport layers 112a and 113a for transporting holes and electrons to the front electrode layer 112 and back electrode layer 113, respectively, as is commonly accomplished in known perovskite photovoltaic cells.

[0034] Depending on the desired operating characteristics and functional materials used in the photovoltaic cell 100, the stack 110 can have various structures. For example, the stack 110 of the photovoltaic cell 100 may have a planar or mesoscopic nip structure, in which the back electrode layer 113 constitutes the cathode layer and the front electrode layer 112 constitutes the anode layer, and thus the charge transport layers 112a and 113a for carrying charges are the electron transport layer 112a between the perovskite layer 111 and the anode layer 112 and the hole transport layer 113a between the perovskite layer 111 and the cathode layer 113, respectively.

[0035] In another embodiment, the stack 110 of the photovoltaic cell 100 may have either a planar or mesoscopic pin structure, in which case the back electrode layer 113 constitutes the anode and the front electrode layer 112 constitutes the cathode, and the charge transport layers 112a and 113a for carrying the charges are therefore a hole transport layer 112a between the perovskite layer 111 and the cathode layer 112, and an electron transport layer 113a between the perovskite layer 111 and the anode layer 113, respectively.

[0036] The work function of carbon is deep (5~ 5.1 eV), it functions as a hole transport layer and as an electrode. Thus, the nip structure is suitable for carbon as the top electrode for hole extraction.

[0037] "Carbon is organic and does not react with the ions transferred from the perovskite layer, which makes the device more stable for longer than metal electrodes. It can be made into a solution that can be processed by conventional techniques such as screen, slot, or doctor blade coating. Carbon is a commercially available and inexpensive material."

[0038] Furthermore, it is possible to perform patterning P4 (more on this below) in a single step through the carbon electrode and other layers on the back side (as opposed to prior art solutions having a metal electrode on the back side which can melt and therefore cannot be removed in a single step with other layers) since the laser beam burns the material of that electrode, causing its complete removal, so there is no risk of contact (bridging) between the top and bottom electrodes. Alternatively, if desired, multi-step patterning P4 can also be used.

[0039] As shown in FIG. 2A, one embodiment of a photovoltaic device is presented, in which the substrate 120 may be in the form of a PET foil, and the photovoltaic cell 100 may be constructed from a nip structured laminate 110.

[0040] The laminate 110 includes a back electrode layer 113 containing carbon and an AZO( Al 2 O3 The photovoltaic cell stack 110 further comprises a charge transport layer 112a for transporting electrons to the cathode 112, the charge transport layer 112 being made of a semi-transparent front electrode layer 112 made of ZnO (Zn-doped ZnO). Nevertheless, other materials may be used as the front electrode layer 112 acting as the anode, a non-limiting group of examples including, for example, ITO (indium doped tin oxide), FTO (fluorine doped tin oxide) or DMD (dielectric / metal / dielectric) structures, for example ITO / Ag / ITO. SnO 2 (tin dioxide), and a charge transport layer 113a for propagating holes to the carbon anode 113 is made of PTAA (poly(trialkylamine)). SnO 2 may be replaced with various other materials, such as TiOx, ZnO, PCBM, or OXD-7. The same is true for the PTAA material, which may be replaced with, for example, NiOx (nickel oxide), CuSCN (copper thiocyanate ( I )), CuO(copper oxide ( II )), MoOx (molybdenum oxide), PEDOT (poly(3,4-ethylenedioxythiophene)), P3HT (poly(3-hexylthiophene-2,5-diyl)) or Spiro-OMeTAD (N2,N2, N2' ,N7, N7' -Octakis(4-methoxyphenyl)-9, 9' -Spirobi[9H-fluorene]-2, 2' ,7, 7' -tetramine).

[0041] For nip device structures where a carbon-containing back electrode layer 113 is disposed as the cathode, other non-limiting examples of charge carrier layers can be used. For example, the charge carrier layer 113a for transporting holes to the carbon cathode layer 113 may be selected from the group consisting of NiOx, CuSCN, CuO, MoOx, PEDOT, P3HT, Spiro-OMeTAD, and PTAA (poly(triarylamine)).

[0042] Here, for example, the surface charge transport layer 112a for transporting electrons to the anode surface layer 112 may be selected from the group consisting of bayes, TiOx (titanium oxide), ZnO (zinc oxide), PCBM (phenyl-C61-butyric acid methyl ester) or OXD-7 (1,3-bis[2-(4-tert-butylphenyl)-1,3,4-oxadiazo-5-yl]benzene), SnOx (tin(ll)).

[0043] In another embodiment of the photovoltaic device according to the present disclosure, a back electrode layer 113 comprising carbon may be implemented as the anode. So far, carbon has only been reported in nip configurations. The inventors of the present disclosure have found that it is possible to fabricate pin devices with carbon as the top electrode by providing a buffer layer between the n-type layer and the carbon for efficient electron transport.

[0044] In yet another embodiment of the present invention, as shown in FIG. 2B, at least one additional passivation layer may be incorporated into the photovoltaic device 100 between the photoactive layer 111 and the charge transport layer 112a, 113a: a front passivation layer 112b, and / or a back passivation layer 113b. The passivation layer 112b, 113b acts as a means to reduce or suppress non-radiative recombination at the interface between the photoactive material 111 and the charge transport layer 112a, 113a. This can be achieved by ionic bonding, material coordination, or converting the surface to a region wider than the band gap of the photoactive material 111. This can be achieved by ionic bonding, material coordination, or converting the surface to a region wider than the band gap of the photoactive material 111. The passivation layer 112b, 113b may be composed of materials selected from the following groups: Lewis acids and bases, anions and cations, zwitterions, semiconductors and insulators. Non-exhaustive examples include perovskite materials with a different composition than the bulk of the photoactive layer, insulators (polymers such as PMMA (polymethyl methacrylate), small molecules such as BCP (bathocuproine), PCBM and its derivatives, SAMs (Self Assembly Monolayers), etc.), ionic materials, etc. NaCl, Kl , and AlOx ( Al 2 O 3 The thickness of the passivation layers 112b, 113b can be selected as needed to improve photovoltaic performance, but their presence does not significantly affect the steps required to fabricate the semi-transparent device via laser patterning.

[0045] A non-limiting example of a perovskite material that can be used in both pin and nip structures is the 3D ABX 3 Perovskite structure, which has corner-sharing BX 6 It consists of a network of octahedra, with the B atoms being divalent metal cations (typically Ge 2+ , Sn 2+ or Pb 2+ ), X is a monovalent anion (typically Cl - , Br - , I - ) The A cation is chosen to balance the total charge, and Cs + Or it becomes a low molecular weight species. Two-dimensional perovskites are classified into Ruddlesden-Popper type and Dion-Jacobson type, and their crystal structures are represented by the general formula R 2 A n-1 B n X 3n+1 It is expressed as: Here, R is a bulky organic cation, such as phenylethylammonium (PEA). + ) and butylammonium (BA + ) is the most widely used R cation.

[0046] The carbon-containing back electrode layer 113 is made of carbon (and possibly additional inorganic additives for performance enhancement). The carbon layer may be flexible by including a polymer binder that binds the carbon black and the conductive graphite flakes. Furthermore, the layer is thin, preferably about 20 μm. To form the carbon-containing back electrode layer 113, the carbon material may be provided in the form of a paste. The carbon layer 113 may be formed by applying a carbon paste as the back contact deposition layer. The basic components of the paste are carbon black, graphite, a polymer binder, and a compatible system with perovskite.

[0047] For example, a carbon paste such as that mentioned in Patent Document 1 (CN104966548) can be used, which has a solvent system: isopropanol, ethyl acetate, and chlorobenzene. The binder of the slurry is acrylic resin or ethyl cellulose, the conductive filler is flake graphite, the catalyst is nanocarbon black powder, and the inorganic additive is ZrO 2 and NiO are used.

[0048] The carbon paste can be deposited onto the device stack using a semi-automatic screen printer. A screen with a polyester mesh size of 156-250 threads / inch and a screen tension of 25 N / cm or higher can be selected for the printing process. After deposition, the film can be annealed with an infrared emitter to remove the solvent and improve the conductivity.

[0049] figure 1B 1A and 1B show a semi-transparent photovoltaic device according to one embodiment of the present disclosure; 1B FIG. 1C shows a schematic of the device in a top view and FIG. 1C shows two cross-sectional views along lines AA and BB of the photovoltaic device.

[0050] A photovoltaic device is comprised of at least one photovoltaic cell 100, but may preferably be comprised of two or more photovoltaic cells 100.1B 1C shows a photovoltaic device consisting of two photovoltaic cells 100. Nevertheless, a photovoltaic device may consist of more than two photovoltaic cells 100. The number of photovoltaic cells 100 implemented in one photovoltaic device depends on the engineering requirements, the available area and the rational design (losses due to sheet resistance).

[0051] At least one photovoltaic cell 100 in the photovoltaic device is semi-transparent, preferably 50% or more of the photovoltaic cells 100 in the photovoltaic device are semi-transparent, and more preferably all of the photovoltaic cells 100 in the photovoltaic device are semi-transparent.

[0052] Each light-transmitting photovoltaic cell 100 of the photovoltaic device is composed of at least one semi-light-transmitting aperture 130, and preferably multiple semi-light-transmitting apertures 130, formed in a stack 110 of layers of photovoltaic cells disposed on a substrate 120.

[0053] figure 1B 1 illustrates a non-limiting example of an arrangement of semi-transparent apertures 130 in a photovoltaic cell 100.

[0054] The semi-transparent aperture 130 provides the optical transparency of the photovoltaic device. Thus, the larger the area (further referred to as the transparent area) occupied by the semi-transparent aperture 130, the more optically transparent the photovoltaic device is.

[0055] The semi-transparent apertures 130 in the stack 110 of photovoltaic cell working layers provide a reduction in the working area of ​​the photovoltaic cells, so that the transparent area ratio preferably constitutes 10-90% of the total area of ​​each photovoltaic cell, depending on the specific requirements for the application and module design, thereby providing suitable properties with visible translucency for the photovoltaic device.

[0056] Preferably, the transparent area ratio is selected according to individual needs, depending on the required light transmittance and performance of the photovoltaic device.

[0057] The photovoltaic cells 100 are preferably electrically connected to each other by a junction between the anode of one photovoltaic cell and the cathode of another photovoltaic cell.

[0058] Each semi-transparent aperture 130 is formed by laser beam processing in a single operation, such that the laser beam penetrates the laminate 110 and thus removes material of the stack. It has been found that the use of a carbon back electrode layer 113 makes it possible to eliminate the delamination effect at the edges of the apertures 130, as exists in prior art solutions.

[0059] Furthermore, when all layers of the stack 110 are removed, the removal of both the front and back electrode layers provides increased transparency of each formed semi-transparent aperture 130 and therefore the entire photovoltaic device.

[0060] The substrate 120 is not affected by the laser beam while forming the semi-transparent aperture 130, and layers can be removed without damaging the substrate, due to optimized laser parameters (shown in Table 1 below). Using high laser powers can damage the substrate, and low powers cannot completely remove the layers. Thus, the substrate 120 remains continuous after the laser process, forming a barrier that protects the interior of the photovoltaic device from the environment. The substrate 120 is not affected by the laser beam while forming the semi-transparent aperture 130, and layers can be removed without damaging the substrate, due to optimized laser parameters (shown in Table 1 below). Using high laser powers can damage the substrate, and low powers cannot completely remove the layers. Thus, the substrate 120 remains continuous after the laser process, forming a barrier that protects the interior of the photovoltaic device from the environment.

[0061] The method for manufacturing a semi-transparent photovoltaic device includes providing a light-transmitting substrate 120, such as a plastic foil, and forming a stack 110 of working layers of a photovoltaic cell(s) by successive deposition and laser patterning steps P1-P4, as described below. For example, as shown in FIG. 1C, a step of removing the front electrode by laser patterning P1 may be performed to create separate cell regions. For example, as shown in FIG. 1C, a step of removing the front electrode by laser patterning P1 may be performed to create separate cell regions. For P1 patterning, different lasers can be used depending on the material of the front electrode, for example, in the case of transparent conductive oxide (TCO), an infrared laser can typically be used. A second laser patterning P2, may be required after deposition of a surface charge transport layer 112a on the front electrode layer 112, which can be either an electron transport layer or a hole transport layer, either pin or nip, depending on the structure of the photovoltaic cell. Laser patterning P2 locally removes the charge transport layer 112a. Typically, the patterning of P2 can use an IR or other visible laser. The manufacturing method of a semi-transparent photovoltaic device includes providing a light-transmitting substrate 120, such as a plastic foil, and forming a stack 110 of working layers of a photovoltaic cell(s) by successive deposition and laser patterning steps P1-P4, as described below. For example, as shown in FIG. 1C, a step of removing the front electrode by laser patterning P1 may be performed to create separate cell regions. For example, as shown in FIG. 1C, a step of removing the front electrode by laser patterning P1 may be performed to create separate cell regions. For P1 patterning, different lasers can be used depending on the material of the front electrode, for example, in the case of transparent conductive oxide (TCO), an infrared laser can typically be used. A second laser patterning P2 may be required after deposition of a surface charge transport layer 112a on the front electrode layer 112, which can be either an electron transport layer or a hole transport layer, either pin or nip, depending on the structure of the photovoltaic cell.Laser patterning P2 locally removes the charge transport layer 112a. Typically, the patterning of P2 can use an IR or other visible laser.

[0062] Next, a carbon opaque back electrode layer 113 is deposited and a patterning step P3 is carried out to define the boundaries of and separate the individual cells.

[0063] After completion of the P3 patterning step, the carbon layer forms the back electrode layer 113, and such devices consist only of opaque (non-transmitting) photovoltaic cells due to the presence of the continuous carbon back electrode layer 113, which is itself opaque.

[0064] The stack 110 is then laser patterned P4 to form at least one, and preferably multiple, semi-transparent apertures 130 in the stack 110 of working layers in the photovoltaic cell 100, such that the apertures 130 extend through at least the back electrode layer 113 and at least a part of the perovskite photoactive layer 111. This makes the solar cell semi-transparent. Optionally, to further improve the semi-transparent properties, the apertures 130 may extend through all layers of the stack 110, from the back electrode layer 113 to the front electrode layer 112.

[0065] In P4 patterning, the laser impacts the stack 110 on the opposite side from the substrate 120. Each semi-transparent aperture 130 is created in one laser processing step, such that the laser beam penetrates the layer of the stack 110 of photovoltaic cells that is to be removed along the depth of the aperture 130 one time.

[0066] As a result, the semi-transparent aperture 130 is completely surrounded by the layer stack 110 that contributes to power conversion (in other words, by the active area of ​​the solar cell), i.e., all layers are directly adjacent to the aperture 130 and adjacent to each other along the vertical walls of the aperture 130 (in contrast to the prior art, where the top layer of the stack is away from or peeled away from the aperture wall).

[0067] By forming the aperture 130 in a single laser patterning step P4, the cross-section of the aperture 130 along its depth is substantially uniform (i.e., it forms a well with substantially straight sidewalls that narrow slightly towards the bottom).

[0068] The formation of the semi-transparent apertures 130 penetrates from the front side to the back side layers of the stack 110, each in a single step, similarly providing method simplification and shortening of the manufacturing process. In P4 patterning, the laser beam does not affect the substrate. This is achieved by optimizing the laser parameters. Furthermore, after the apertures 130 are formed, at least a portion of the apertures 130 may be filled with a functionalizing agent, such as an ink or pigment, that can provide a color appearance for the photovoltaic cell.

[0069] The aforementioned enhancements in semi-transparent photovoltaic devices are brought about by the developed photovoltaic cell stack 110 structure, namely the implementation of a carbon-containing back electrode layer 113, which is inherently opaque, but becomes semi-transparent only by laser processing - due to the presence of laser-made semi-transparent apertures 130.

[0070] It is believed that the carbon material contained in the back electrode layer 113 undergoes complete oxidative combustion due to the laser treatment. Thus, the carbon material is removed by the laser without contaminating the inside of the semi-transparent aperture 130 with by-products of the interaction between the laser and the carbon. Unlike the metal materials commonly used for the opaque back electrode layer, carbon probably does not melt or vaporize upon interaction with the laser beam, thereby providing the above-mentioned effects. Therefore, according to the present method, the semi-transparent aperture 130 does not constitute an unremoved residue of the back electrode layer 113, which further realizes the elimination of short circuit effects and peeling of the carbon layer (because the carbon layer does not melt).

[0071] The developed method also has the additional advantage of providing transparency by forming semi-transparent apertures 130 through the working layer of the solar cell. In particular, photovoltaic devices obtained by the method according to the present disclosure can exhibit various conductivity of materials for the back electrode layer. A thicker layer reduces the resistance and increases the conductivity, but the material cost is high. This delicate balance is optimal for both device performance and reasonable cost. Conductive silver and copper pastes are also commercially available, and thick films can be formed by screen printing. However, P3 is not preferred because it requires high power to remove layers with a thickness of microns, which may damage the bottom electrode. Also, P4 laser for transparency is not suitable because it may melt the bottom electrode and cause a short circuit. For this reason, research is being conducted to form thin metal electrodes up to 100 nm that are suitable for removal by P3 laser to form high fill factor devices.

[0072] Furthermore, the use of carbon materials eliminates the need for additional lateral conductive layers, as is required in conventional metal grid approaches. To form the semi-transparent aperture 130 through which light passes, the perovskite layer used can be thicker - as the perovskite material does not constitute a light barrier in the developed structure. A thicker perovskite active region can absorb more light and generate a higher photocurrent.

[0073] Furthermore, due to the implementation of a carbon layer instead of a metal as the back electrode layer 113, a standard inexpensive laser can be used to achieve the formation of the semi-transparent aperture 130. The developed method does not require the use of more expensive picosecond or femtosecond lasers, thus providing a reduction in the overall manufacturing cost.

[0074] For example, according to this method, an IR laser can be used in the P4 patterning step, and is therefore the same as that used in the P1 to P3 patterning steps.

[0075] The array of semi-transparent apertures 130 can be formed into a variety of patterns depending on a particular need, and the array may take the form of a variety of aesthetic creations.

[0076] The semi-transparent apertures 130 may be of various shapes obtained by the laser light. Nevertheless, preferably, the photoactive areas, i.e. the non-transparent areas of the stack 110 of each translucent photovoltaic cell, are electrically continuous. In other words, the photoactive (opaque) areas thereby take the form of continuous paths running between the semi-transparent apertures 130 and are able to collect all the charges generated in the photovoltaic cells.

[0077] Preferably, the semi-transparent apertures 130 are circular in shape, uniformly or non-uniformly distributed within the photovoltaic cell. The semi-transparent apertures 130 may be of various areas depending on the need for translucency, while the areas of the semi-transparent apertures 130 may vary within a single photovoltaic cell. Preferably, each semi-transparent aperture 130 is 1 μm 2 ~1000cm 2 , and the spacing between the two nearest semi-transparent apertures 130 (depending on the resolution of the laser) may be in the range of 1 μm Multiple laser spots in the range of ~100 cm can be formed adjacent to each other or overlap each other.

[0078] A substantially uniform distribution of semi-transparent apertures 130 whose areas and spacings fall within the ranges given above can give a user the impression of translucency (semi-transparency) of the entire photovoltaic device on a macroscopic scale, due to the selected dimensions and spacing of the semi-transparent apertures 130.

[0079] Therefore, the semi-transparent photovoltaic device can be used to cover the glass panels of a building. Example: Fabrication of semi-transparent photovoltaic device with nip-type photovoltaic cell structure.

[0080] This semi-transparent photovoltaic device was fabricated by combining Eastman AZO (300 nm) as the front electrode layer on a flexible PET substrate and fabricating a foil from the PET and AZO. The remaining layers of the photovoltaic cell stack were deposited in order by spin coating. SnO 2 (electron transport layer), stoichiometric ratio Cs 0.05 (MA 0.17 FA 0.83 ) 0.95 Pb(I 0.83 Br 0.17 ) 3 The perovskite (perovskite photoactive layer) was deposited in the order of Cs, MA, FA0.83, formamidinium, Pb, lead, I, iodine, Br, bromine, and PTAA (as a hole transport layer). The back electrode layer is blade-coated with EMS carbon paste (CI-2042) and cooled to 80°C by gas quenching. ℃ The carbon paste was annealed for 5 minutes at each temperature. The thickness of the carbon paste measured by FIB-SEM was 20 μm So, about 20 Ω / sq The sheet resistance of 200 mm diameter was obtained. μm , interval 500 μm This was achieved by ablating a matrix of semi-transparent apertures (spots) of 100 nm. Laser ablation was performed in a manner that did not disturb the PET substrate. The parameters used for laser patterning are listed in Table 1 below.

[0081] (Table 1) Parameters used for laser patterning TIFF0007623013000001.tif51141

[0082] FIG. 3 is a photograph of the entire semi-transparent photovoltaic device obtained, and it can be seen that the formed aperture provides light transmission. Next, SEM photographs were taken to examine the details of the formed aperture. The SEM photographs shown in FIG. 4A to FIG. 4C were taken with a scanning electron microscope (SEM). As can be seen from the photographs, the aperture has a diameter of 200 mm. μm of circular regular shape and no visible peeling effect.

[0083] During further investigation, cross-sectional FIB-SEM (Focused Ion Beam - Scanning Electron Microscope) images of the structure inside the semi-transparent aperture (130) were presented, showing the complete removal of the stack (110) (Image 1) and revealing the active layer stack (110) (Image 2).

[0084] In Image 1 of Figure 6, it can be seen that the laser pulse ablates all the layers down to the substrate.

[0085] The resulting device was then subjected to a JV reverse scan to evaluate the JV characteristics, which confirmed that the device was functional and generating electricity, as shown in Figure 5B.

[0086] Furthermore, the transmittance of this device was measured, and the results are shown in Figure 5A. As a result, it was confirmed that the device transmits light.

Claims

1. A photovoltaic cell according to claim 1, further comprising: a semi-transparent substrate and at least one semi-transparent photovoltaic cell; The photovoltaic cell includes a stack disposed on the semi-transparent substrate, the stack including: a front electrode layer constituting an anode layer; A rear carbon electrode layer constituting a cathode layer; and a perovskite photoactive layer between the anode layer and the cathode layer; The rear carbon electrode layer contains carbon black, graphite, and a polymer binder as basic components, the stack of photovoltaic cells having a semi-transparent laser machined aperture through at least the back carbon electrode layer and the perovskite photoactive layer of the photovoltaic cell; A semi-transparent photovoltaic device, wherein the semi-transparent aperture is completely surrounded by the stack that contributes to power conversion, such that the stack of photovoltaic cells is electrically continuous.

2. The semi-transparent substrate is flexible. The semi-transparent photovoltaic device of claim 1 .

3. The laminate comprises: a front charge transport layer disposed between the perovskite photoactive layer and the front electrode layer; a back charge transport layer disposed between the perovskite photoactive layer and the back carbon electrode layer, 3. A semi-transparent photovoltaic device according to claim 1 or 2.

4. a front passivation layer between the perovskite photoactive layer and the front charge transport layer, and / or a back passivation layer between the perovskite photoactive layer and the back charge transport layer, The semi-transparent photovoltaic device of claim 3 .

5. The semi-transparent photovoltaic device of claim 1 , wherein the back carbon electrode layer has a thickness of 10 nm to 1000 μm.

6. The photovoltaic cell includes a plurality of the photovoltaic cells, each of which has 1 μm ２ From 1000cm ２ The semi-translucent aperture formed by the laser processing has an area of ​​1 μm to 100 cm, and the interval between two adjacent semi-translucent apertures is 1 μm to 100 cm. A semi-transparent photovoltaic device according to any one of claims 1 to 5.

7. The photovoltaic cell has an nip structure. A semi-transparent photovoltaic device according to any one of claims 1 to 6.

8. In the laminate, the front electrode layer comprises AZO; the front charge transport layer comprises SnO 2 ; the perovskite photoactive layer comprises a perovskite material; the back charge transport layer comprises PTAA; The back carbon electrode layer comprises carbon; The semi-transparent photovoltaic device of claim 3 .

9. Providing a semi-transparent substrate; forming a stack of photovoltaic cells on the substrate; and The laminate comprises: A front electrode layer constituting an anode, a back carbon electrode layer constituting a cathode, and a perovskite photoactive layer between the front electrode layer and the back carbon electrode layer, The step of forming the stack of photovoltaic cells comprises: forming the back carbon electrode layer from a carbon paste whose basic components are carbon black, graphite, a polymeric binder and a solvent system compatible with the perovskite; The method further includes laser patterning semi-transparent apertures in the stack of photovoltaic cells; the semi-transparent aperture extends through at least the back carbon electrode layer and at least a portion of the perovskite photoactive layer and is completely surrounded by the stack that contributes to power conversion, such that the stack of the photovoltaic cell is electrically continuous; Manufacturing method.

10. each of the semi-transparent apertures is formed by single-step laser patterning; The method of claim 9.

11. The semi-transparent aperture is formed using a nanosecond IR laser. The method according to claim 9 or 10.

12. The semi-transparent aperture is formed in a plurality of the stacks of the photovoltaic cells. The method according to any one of claims 9 to 11.

13. The semi-transparent aperture is 1 μm ２ From 1000cm ２ and has an area of The method according to claim 9 , wherein the distance between two adjacent semi-transparent apertures is from 1 μm to 100 cm.

14. The step of forming the laminate further comprises: forming a front charge transport layer between the perovskite photoactive layer and the front electrode layer; forming a back charge transport layer between the perovskite photoactive layer and the back carbon electrode layer. The method according to any one of claims 9 to 13.

15. The step of forming the laminate further comprises: a front passivation layer between the perovskite photoactive layer and the front charge transport layer; and / or forming a backside passivation layer between the perovskite photoactive layer and the backside charge transport layer; The method of claim 14.

16. The step of forming the back carbon electrode layer includes: Preparing a carbon paste; forming a carbon layer as a top layer of the stack of photovoltaic cells; and drying the carbon layer in the laminate to form the back carbon electrode layer. The method according to any one of claims 9 to 15.

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