Laminated electrode for perovskite solar cells

Abstract

This disclosure relates to a novel hole-collecting laminated electrode presented for perovskite solar cells. The hole-collecting electrode comprises a nanoparticle hole¬ transport layer, and a conductive back sheet, where the gap between them is filled with a conductive adhesive. The application of the back sheet electrode on top of the nanoparticle HTL involves a wet application process, where a conductive adhesive ink is applied, while the conductive back sheet is lying on the HTL, in a way that ink completely dries while the sheet is applied on the surface. The adhesive ink includes a solvent, a binder, a conductive carbon nanoparticle as filler, semiconductor nanoparticles such as metal oxide or chalcopyrite for effective charge transfer, and modifying agents as additives to add additional properties to the ink.

Description

DescriptionTitle of Invention: LAMINATED ELECTRODE FOR PEROVSKITE SOLAR CELLSTechnical Field[1] The present invention relates to the fabrication technology of perovskite solar cells, and more specifically to a preparation method for a hole-collecting electrode in perovskite solar cells.Background Art[2] Perovskite solar cells (PSCs) have emerged as a revolutionary technology in the field of photovoltaics, offering a promising alternative to traditional silicon-based solar cells. These cells utilize perovskite-structured materials, which exhibit exceptional light absorption, charge-carrier mobilities, and tunable bandgaps, leading to high power conversion efficiencies. Since their inception, PSCs have rapidly progressed, achieving efficiencies exceeding 25% in laboratory settings, comparable to conventional silicon solar cells. Beyond their impressive performance, perovskite solar cells are also attractive due to their potential for low- cost production and ease of fabrication, which includes solution processing and printing techniques. This positions PSCs as a versatile and scalable solution for sustainable energy, with ongoing research focusing on enhancing their stability and commercial viability to fully realize their potential in the global energy market.[3] Perovskite solar cells can be designed in two primary architectures: n-l-p and p-i- n, each denoting the sequence of layers involved in charge transport. In the n-i-p configuration, the structure consists of an n-type electron transport layer (ETL) at the bottom, followed by the intrinsic perovskite absorber layer (i), and a p-type holetransport layer (HTL) at the top, culminating with a metal or carbon electrode. In this arrangement, holes are collected through the HTL, electrode bilayer, referred to as the hole collection electrode. Conversely, the p-i-n configuration reverses this order, starting with a p-type HTL at the bottom, followed by the intrinsic perovskite layer, and then an n-type ETL at the top, ending with the metal electrode. This invention pertains to a new hole collection electrode assembly in n-i-p perovskite solar cells.[4] The hole-collecting electrode consists of the hole transport layer (HTL) and the metal electrode. The HTL, placed on top of the intrinsic perovskite layer, functionsto extract and transport holes while blocking electrons to prevent recombination. Commonly used organic hole transport materials (HTMs) include Spiro-OMeTAD, which is highly effective due to its excellent energy level alignment, high hole mobility, and good film-forming properties. However, Spiro-OMeTAD requires doping with additives like lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI) and tert-butylpyridine (tBP) to enhance its conductivity, which can lead to stability issues. Inorganic HTMs, such as nickel oxide (NiO) and copper thiocyanate (CuSCN), offer promising alternatives due to their intrinsic stability, lower cost, and compatibility with scalable fabrication processes. However, these materials face challenges in reproducible and effective deposition.[5] Using nanoparticles as the hole transport layer (HTL) in perovskite solar cells offers several notable advantages. Nanoparticles can provide higher hole mobility compared to conventional organic HTMs. This can lead to more efficient charge extraction and transport. The energy levels of nanoparticle-based HTLs can be tailored to match the perovskite material, facilitating better energy alignment and more efficient hole extraction. Inorganic nanoparticles, such as those made from Cu(ln, Ga)S2 are more chemically stable than many organic HTMs. Nanoparticle HTLs can withstand higher temperatures without degrading, which is beneficial for both the manufacturing process and the operational stability of the solar cells. Besides, many nanoparticles are made from abundant and inexpensive materials, which can reduce the overall cost of the HTL compared to traditional organic materials. Nanoparticles can also be used in flexible perovskite solar cells, expanding the potential applications of these cells to include wearable electronics, portable devices, and building-integrated photovoltaics. In this invention, we employ nanoparticles as HTL in the hole-collecting electrode.Summary of Invention[6] This patent application discloses a novel method for manufacturing a holecollecting electrode for n-i-p perovskite solar cells. The method may involve depositing a hole-transport layer (HTL) comprising inorganic semiconductor nanoparticles on top of a perovskite layer to form a substrate with sequential layers including glass, transparent conductive oxide (TCO), electron transport layer (ETL), perovskite, and the HTL. The HTL nanoparticles may be dispersed in a non-polar solvent and applied atop the perovskite layer. A conductive adhesive ink,comprising a non-polar solvent, conductive filler, polymer binder, and semiconductor nanoparticles, is then used to adhere a laser-patterned conductive back sheet to the HTL. The process may employ a wet application technique where the conductive adhesive ink is applied over the HTL, followed by continuous application of the back sheet using a roll-press, with temperature tuning to regulate solvent evaporation and ensure proper incorporation of the adhesive.[7] The conductive adhesive ink's non-polar solvent can be selected from a group including chloroform, chlorobenzene, toluene, and xylene. The conductive filler can be carbon black or acetylene black, while the polymer binder is a perovskite passivating polymer such as polymethylmethacrylate (PMMA). The HTL can include Cu (In, Ga) S2 nanoparticles capped with oleylamine ligands and may be deposited using various ink deposition methods such as spin coating, blade coating, and slot-die coating. The conductive back sheet, which can be patterned by laser or mechanical means, is chosen from materials such as carbon foils, metal foils, metal-coated plastic films, or conductive mesh, ensuring optimal performance and stability of the solar cell.[8] Additionally, the application details the composition of the hole-collecting electrode, which includes the HTL containing inorganic semiconductor nanoparticles laminated on top of the perovskite layer using the conductive adhesive ink. The ink comprises a non-polar solvent, a conductive filler, a polymer binder, and semiconductor nanoparticles, specifically Cu (ln,Ga)S2 nanoparticles. This innovative approach addresses the challenges of manufacturing and scaling up perovskite solar cells, offering a cost-effective and stable solution for commercial implementation.Technical Problem[9] In n-i-p perovskite solar cells according to prior art, a metal (or carbon) layer is deposited on top of the HTL to collect the photo-generated current. Gold is conventionally employed as the metal electrode in lab-scale perovskite solar cells. Other metals, such as Ag or Cu, have been used; however, they have severe stability problems and cannot be considered for scale-up and manufacturing. However, gold is an expensive material, which increases the overall cost of manufacturing perovskite solar cells. Cheaper alternatives are desirable for large-scale production. In addition, while Au electrodes can achieve high power conversion efficiency, they can accelerate device degradation over time. The interaction between Au and other layers can lead to performance loss and reduced stability. Also, Au is mainly deposited using the vacuum evaporation methods which is not a scalable manufacturing method. Sputtering of Au is a more manufacture-friendly technique for the scale-up of perovskite solar cells; however, sputtered Au electrodes may damage the organic hole transport layer (HTL) and the perovskite layer, affecting overall device performance. Therefore, a monolithic carbon electrode could be a more appropriate electrode, compared to gold, in a hole collecting electrode. Using pasted carbon as an electrode material can indeed reduce the cost and improve the stability of perovskite solar cells. However, there are critical issues to consider. Carbon electrodes may exhibit inferior performance due to poor interface contact between the carbon material and the perovskite layer. This can affect the overall efficiency of the photovoltaic device. Furthermore, the inherent resistance of carbon electrodes can lead to suboptimal series resistance of the devices, and this will reduce the fill factor and efficiency of solar cells.

[0010] To achieve the above objects, in an exemplary implementation, a laminated electrode can be utilized in this invention for the back contact in the hole collecting electrode. The lamination process may involve pressing or adhering a conductive back sheet onto the HTL (in n-i-p perovskite cells), by using a conductive adhesive ink in between.

[0011] In the conventional art of laminated organic or perovskite solar cells, the electrode sheet is first coated with the conductive adhesive ink, then the thick film is dried, and the coated sheet is applied on the HTL by pressing (usually hot pressing). During this process, the conductive adhesive should flow in the gap between out of the HTL and to the conductive back sheet to make sufficient contact points for charge transfer out of HTL, to the conductive back sheet. This is a tricky process, as the conductive adhesive usually does not sufficiently flow, resulting in insufficient electrical contact points. This is because high temperature and high pressure cannot be used for the process, since high temperature may degrade underlying device layers, and high pressure may damage the device or break the glass substrate. To achieve the objectives mentioned above, this invention claimsto manufacture a hole-collecting electrode (200) using a wet application process with a new conductive adhesive ink.Solution to Problem

[0012] Perovskite solar cells with laminated electrodes represent an innovative advancement in photovoltaic technology, combining the high efficiency of perovskite materials with the flexible and scalable advantages of laminated electrode techniques. These solar cells utilize a perovskite layer known for its excellent light-absorbing and charge-transport properties, sandwiched by a laminated electrode that enhances structural integrity and allows for flexible applications.

[0013] In an exemplary implementation, the present disclosure is directed to a lamination process to form the hole collecting electrode which can be an HTL, electrode bilayer, involves pressing or adhering a conductive back sheet as the electrode onto the hole transport layer (HTL) in n-i-p perovskite cells, by using a conductive adhesive ink in between. Lamination simplifies manufacturing, reduces production costs, and enables the creation of lightweight, bendable solar panels. This approach not only improves the mechanical durability of the cells but also facilitates the integration of solar technology into a variety of surfaces and devices, potentially revolutionizing the deployment of solar energy in both conventional and novel contexts.

[0014] In an exemplary implementation, the hole transport layer may comprise the semiconductor nanoparticles.

[0015] In an exemplary implementation, the conductive adhesive ink serves for electrically and mechanically connecting the conductive back sheet with underlying hole transport layer which briefly is written as the HTL. In general, the conductive adhesive ink may comprise a non-aqueous solvent, a binder, the conductive carbon nanoparticles as a filler, the semiconductor nanoparticles as charge transfer agents, and conventional rheology, wetting, and adhesion ink additives.

[0016] In the conventional art, a dry conductive adhesive on the conductive back sheet is provided, and no solvent is used in the application process.

[0017] In the conventional art of laminated perovskite and organic solar cells, PEDOT : PSS is employed as the conductive organic filler, by which the charge istransported from the HTL to the top conductive back sheet. PEDOT: PSS is easy to process and has excellent electrical conductivity. The disadvantage of PEDOT: PSS is the acidic character which degrades the perovskite layer over time, resulting in device instability. Other materials have also been employed as the conductive filler of the adhesive. Carbon black, carbon nanotubes, graphene, and silver nanowires are some materials reported as conductive fillers. For PEDOT: PSS conductive adhesives, sorbitol is usually used as the binder. Sorbitol provides adhesion, as well as, doping of the PEDOT: PSS, improving both mechanical and electrical properties.

[0018] In this invention, a wet application process may be used, wherein a roller may lie the conductive back sheet at a slow speed, and the conductive adhesive ink may be injected between the HTL and conductive back sheet gap. It is usually needed to slightly increase the temperature (up to about 100°C) to increase the evaporation rate of the solvent. Temperature, roller speed, and ink injection should be carefully tuned to achieve optimal results. It is important to provide an electrode with low-cost materials and a simple fabrication process that does not degrade perovskite or hamper the cell’s stability with efficiencies competing with that of cells with gold electrodes.Advantageous Effects of Invention

[0019] It is important to emphasize that reported methods of electrode lamination differ from the present invention in at least three issues:

[0020] In prior art, the ink is applied over the back sheet, dried, and then laminated using a dry application process (typically hot pressing). In contrast, the lamination process in this invention is a wet application, which has demonstrated superior results in our case.

[0021] The HTL in the present invention comprises inorganic p-type semiconductor nanoparticles which exhibit better stability and can be more easily processed in manufacturing processes. Conversely, in prior art, the HTL material consists of organic semiconductors.

[0022] The conductive adhesive ink contains nanoparticles identical to those in the HTL, thereby enhancing the charge transfer properties.Brief Description of Drawings

[0023] The novel features which are believed to be characteristic of the present disclosure, as to its structure, organization, use, and method of operation, together with further objectives and advantages thereof, will be better understood from the following drawings in which a presently preferred embodiment of the present disclosure will now be illustrated by way of example. It is expressly understood, however, that the drawings are for illustration and description only and are not intended as a definition of the limits of the present disclosure. Embodiments of the present disclosure will now be described by way of example in association with the accompanying drawings in which:

[0024] [FIG. 1] illustrates an example schematic representation of a laminated perovskite solar, consistent with one or more exemplary embodiments of the present disclosure.

[0025] [FIG. 2] shows a hole-collecting electrode formed on top of the perovskite layer of the laminated perovskite solar cell, consistent with one or more exemplary embodiments of the present disclosure.

[0026] [FIG. 3] includes a block diagram illustrating the method of forming the holecollecting electrode, consistent with one or more exemplary embodiments of the present disclosure.

[0027] [FIG. 4A] illustrates an industrial-scale wet application process for large-area processing of perovskite solar cells, with conductive adhesive ink application on HTL, consistent with one or more exemplary embodiments of the present disclosure.

[0028] [FIG. 4B] shows an industrial-scale wet application process for large-area processing of perovskite solar cells, with conductive adhesive ink application on the back sheet foil, consistent with one or more exemplary embodiments of the present disclosure.

[0029] [FIG. 5] depicts a scanning electron microscope (SEM) image of the conductive adhesive ink deposited on carbon foil, consistent with one or more exemplary embodiments of the present disclosure.

[0030] [FIG. 6] is a current density-voltage characterization of perovskite solar cells with Au back contact (gray) versus laminated back contact (black), consistent with one or more exemplary embodiments of the present disclosure;

[0031] [FIG. 7] depicts a table of photovoltaic parameters of forward and reverse scan for perovskite solar cells with Au top electrode and laminated top electrode, consistent with one or more exemplary embodiments of the present disclosure.Description of Embodiments

[0032] The novel features that are believed to be characteristic of the present disclosure, as to its structure, organization, use, and method of operation, together with further objectives and advantages thereof, will be better understood from the following discussion.

[0033] Aspects of the invention are illustrated by way of example and not by way of limitation in the Figures of the accompanying drawings in which references indicate similar elements. It should be noted that references to “an” and “one” embodiment in this disclosure are not necessarily to the same embodiment, and such references mean at least one. In the following description, numerous specific details are set forth to provide a thorough description of the invention. However, it will be apparent to one skilled in the art that the invention may be practiced without these specific details. In other instances, well-known features have not been described in detail so as not to obscure the invention.

[0034] The following description details various embodiments of a hole-collecting electrode 200 for n-i-p perovskite solar cells, a non-aqueous conductive adhesive ink 160 to apply the conductive back sheet 170 onto the HTL 150 (in n-i-p perovskite cells) forming the hole-collecting electrode 200, and a method 300 associated with creating said hole-collecting electrode 200 for n-i-p perovskite solar cells using the resulting conductive adhesive ink 160.

[0035] According to FIG. 2, an embodiment of the present invention provides the hole collecting electrode 200 for n-i-p perovskite solar cells including an electrode 170 laminated over a hole-transporting layer (HTL) 150 using a conductive adhesive ink layer 160. In this embodiment, the HTL 150 can be a layer of inorganic semiconductor nanoparticles (NP) of p-type conductivity (NP-HTL), and the top electrode 170 may be a conductive back sheet laminated over the NP-HTL using the conductive adhesive ink 160.

[0036] In an exemplary embodiment, as shown in FIG. 1 , a perovskite solar cell with n-i-p structure 100 may consist of a consecutive stack of layers; namely, glass layer110, TCO (transparent conductive oxide) layer 120, ETL (electron transport layer) 130, Perovskite layer 140, HTL 150, and a Metal layer 170. The TCO layer 120 can be selected from ITO (indium tin oxide) or FTO (F-doped tin oxide) and may serve as the front electrode. The ETL 130 can be a thin layer of large bandgap n- type semiconductors, such as TiO2, SnO2, or ZnO. The perovskite layer can be any form of lead halide or tin halide perovskite formulation, which acts as the lightabsorbing semiconductor in the solar cell device. In some exemplary embodiment, a conventional formulation of perovskite layer 140 can be CHaNHaPbh, while various modified formulations with multiple cations or anions have been formulated and utilized in perovskite solar cells. This invention is independent of the type of TCO, ETL, and perovskite, as far as the structure of the perovskite solar cell is of n-i-p type.

[0037] In an exemplary embodiment, the hole-collecting electrode 200 may comprise the collection of layers, stacked on top of the perovskite film. It starts with the HTL 150, directly deposited on the perovskite layer 140. Conventionally, the HTL 150 materials may comprise organic polymers (such as PTAA), organic small molecules (such as spiro-OMeTAD), or inorganic dense layers (such as CuSCN or Cu2O). While these HTL materials have their own merits, they are not yet considered for the scale-up of perovskite solar cells, due to stability or manufacturing issues. Inorganic nanoparticles, exhibit better stability and can be more easily processed in manufacturing processes. In this exemplary embodiment, the p-type inorganic nanoparticles as the HTL 150 can be employed.

[0038] In some exemplary embodiments, the HTL 150 comprising inorganic semiconductor nanoparticles 166 which briefly is written as the (NP-HTL) can be of any p-type semiconductor that is synthesized in a stable colloidal ink form. In particular, Culn1 -xGaxS2 (CIGS) comprises a class of p-type semiconductors that exhibit high conductivity and performance in perovskite solar cells. The CIGS composition without Ga inclusion (x=0), will be a simpler formulation of CulnS2 with a bandgap of 1 .5eV. By increasing the x value, the bandgap can be tuned to higher values. A relatively wide range of x has been synthesized and successfully employed as HTL in perovskite cells.

[0039] The CIGS nanoparticles can be synthesized by hot injection processes in oleylamine or other high boiling point liquids. Nanoparticles may be formed byprecipitation reactions at high temperatures. The high temperature ensures the high crystallinity of the synthesized nanoparticles, which is essential to avoid high resistivity HTLs. The synthesized nanoparticles may be then extracted, washed a few times, and then re-dispersed in a non-polar solvent, such as chlorobenzene, toluene, chloroform, or other similar solvents. The outer surface of nanoparticles may remain partly covered by oleylamine ligands, even after several washing processes and dispersing. In some exemplary embodiment, nanoparticles must be capped by a ligand with a long hydrocarbon chain, such as oleylamine. This is important, for both dispersing the nanoparticles in the HTL solvent and also dispersing the nanoparticles in the non-polar conductive adhesive ink 160. These ligands provide steric repulsion among the nanoparticles and prevent agglomeration of nanoparticles in the inks.

[0040] In another exemplary embodiment, additional nanoparticles, such as NiO, CU2O, CuSCN, and other p-type semiconductors, may be synthesized and utilized similarly. For all of these nanoparticles, it is again crucial to cap them with a ligand possessing a long hydrocarbon chain, facilitating their dispersion in non-polar solvents like toluene or chloroform.

[0041] In an exemplary embodiment, the conductive back sheet 170 can be a carbon foil (CNTs, graphite, or graphene), metal foils (such as Al, Ni, stainless steel), metal-coated plastic films (such as aluminum, Ni, Cr, or Ag Nanowires) or conductive mesh (such as stainless steel, Ni, Ag or Cu mesh). The conductive back sheet 170 serves for lateral charge transport to / from the device. As the back sheet exhibits very low resistivity, they lead to low resistive losses in large-scale module devices. In addition to charge transport, the back sheet may serve for encapsulation of the solar cell; protecting the cell from atmospheric humidity or oxygen that are known to chemically damage the perovskite bulk and interfaces.

[0042] A non-aqueous conductive adhesive ink 160

[0043] In an exemplary embodiment, the non-aqueous conductive adhesive ink 160 for the lamination of the hole collecting electrode 200 of perovskite solar cells, may comprise a binder 162, the conductive carbon nanoparticles as filler 164, the semiconductor nanoparticles 166, modifying agents 168, and non-polar solvent.

[0044] The binder 162 may comprise any of the common binders utilized in paste and adhesive formulations. Typically, the binder 162 may consist of one or more polymers that are soluble in non-polar solvents. Examples of such polymers include polystyrene, polymethylmethacrylate (PMMA), and Poly (styrene- butadiene-styrene). Specifically, binder 162 should be chosen from materials containing functional groups such as carbonyl, carboxylic, amine, or others known for passivating the surface of perovskites. PMMA serves as an illustrative example, frequently cited as a passivation agent for perovskite film surfaces.

[0045] The conductive adhesive ink 160 formulation additionally may include at least one conductive filler 164. Carbon black or acetylene black are primary materials recommended for use as the conductive filler 164 due to their small size, which allows for sufficient contact points with the HTL 150 on one side and the back sheet on the other. Other carbon materials, such as graphene, carbon nanotubes, and fullerenes, can also be utilized following appropriate optimizations. Metals, including gold, silver, and other metallic forms, are also viable options. However, when considering metals, it is important to address concerns such as potential reactions with iodide species diffusing from the perovskite.

[0046] The chemical composition of the semiconductor nanoparticles 166 should either match that of the NP-HTL 150 or be of a similar composition. For example, if the NP-HTL 150 comprises CulnS2 (CIS) nanoparticles, the semiconductor nanoparticles 166 in the ink should be CIS or Cu (lnGa)S2. It is considered that the semiconductor nanoparticles 166 are essential for facilitating efficient charge transfer from the HTL 150 to the conductive adhesive ink layer 160. Without semiconductor nanoparticles 166 in the formulation, the current and efficiency of the perovskite devices would significantly diminish.

[0047] The semiconductor can be exemplified by, but not limited to, metal oxides such as copper oxides, titanium dioxide, zinc oxide, and tin oxide; chalcopyrite compounds including copper indium sulfide, copper indium selenide, copper indium gallium selenide, or copper indium gallium sulfide; as well as organic semiconductors such as spiro-OMeTAD or P3HT. This material is tasked with facilitating optimized charge transfer to the conductive laminate.

[0048] The solvent utilized in the conductive adhesive ink 160 may evaporate during the lamination process and leave a solid conductive adhesive in the space between the back sheet 170 and HTL 150. Exemplary solvents comprise but are not limited to, chloroform, chlorobenzene, ethyl acetate, hexane, and toluene.

[0049] The modifying agents 168 are additives employed to impart supplementary properties to the ink, encompassing additives aimed at enhancing wetting, adhesion, viscosity, rheology, bubble inhibition, and similar characteristics. Typically, these additives are introduced to improve the printability of the conductive adhesive ink 160. Examples of modifying agents 168 include but are not restricted to, surfactants and filler particles, such as oxides, sulfides, and graphite.

[0050] Referring to FIG. 3, a block diagram illustrating method 300 of forming the holecollecting electrode 200 of FIG. 2 is shown, according to various embodiments of the present disclosure. Fabrication of the hole-collecting electrode 200 through lamination offers notable advantages, particularly concerning manufacturing. In perovskite solar cell technology, manufacturing and scale-up represent significant challenges that must be addressed before commercial implementation becomes feasible. Various preferred embodiments exist for the lamination process. Referring to FIG. 3, in step 302, the method 300, may include depositing an inorganic semiconductor nanoparticle hole-transport layer (NP-HTL) 150 on top of perovskite layer 140 to form a substrate 502, comprising the step of dispersing nanoparticles in a non-polar solvent and applying said dispersion atop the perovskite layer 140.

[0051] In particular, step 304 may include providing a conductive adhesive ink 160. In an exemplary embodiment, to prepare the conductive adhesive ink 160, initially, the semiconductor nanoparticles 166, the same or slightly modified as the nanoparticles used in step 302 to form the NP-HTL layer may be dispersed in a solvent to form a first mixture. Subsequently, a solution of the thermoplastic polymer as a binder 162 can be separately prepared in the same solvent through simple magnetic stirring to form a second mixture. The first and second mixtures can be combined to yield a final solution comprising one part polymer solution and three parts organic or inorganic semiconductor dispersion. Following this, a weight percentage ranging between 0.5 to 4%wt of carbon nanoparticle powder can be added to the mixture. Employing magnetic stirring once again, a uniform solutionis attained, constituting the final conductive adhesive ink 160. Depending on the modifying agent 168 employed, it can be introduced at any stage within the ink's preparation process.

[0052] In step 306, the method 300, may include providing a conductive sheet of metal or carbon foil or mesh as a back sheet 170.

[0053] In step 310, as illustrated in FIG. 4, method 300, may include applying the conductive adhesive ink 160 over the NP-HTL 150, using a slot die injector 506, maintaining a certain distance from a roller 504. Simultaneously, in step 310, the back sheet foil 170 may continuously be applied over the NP-HTL by using a roll press. In this exemplary embodiment, the substrate 502 with the structure of layers comprising, glass 110, TCO 120, ETL 130, Perovskite 140, NP-HTL 150, moves relative to both the roller 504 and the slot die injector 506 at a predetermined velocity. Referring back to FIGs. 2 and 4, as the substrate 502 moves, the conductive adhesive ink 160 becomes sandwiched between the back sheet 170 and the NP-HTL layer 150. Concurrently, the solvent begins to evaporate at a rate determined by the substrate's temperature. In step 312, the temperature can be controlled by a heater 508 positioned beneath the substrate 502, within a range from room temperature to approximately 100°C. Precise tuning of the substrate's speed, the rate of ink injection, and the temperature are essential to achieve optimal device performance. Specifically, it is crucial in the lamination process to prevent the solvent from being trapped beneath the back sheet.

[0054] In the fabrication of large-sized perovskite solar modules, it is crucial to create ribbon cells interconnected in series. This arrangement reduces module current while boosting module voltage, thereby minimizing resistive losses. In conventional thin film solar cell manufacturing, this is typically achieved through what is known as P1 , P2, and P3 laser scribing at specific stages of fabrication. However, for solar cells featuring a laminated electrode, as claimed in this invention, executing the P3 cut poses a challenge. This difficulty arises due to the significant thickness of the top electrode comprising the back sheet and conductive adhesive, which can reach several tens of micrometers. Achieving selective laser scribing without damaging the TCO (transparent conductive oxide) presents a considerable technical obstacle.

[0055] In the present invention, this issue is tackled through laser patterning of the back sheet foil 170 before its lamination onto the NP-HTL layer 150 in step 308 as shown in FIG. 3. This method is illustrated schematically in FIG. 4A, representing one of the preferred lamination embodiments. In this particular embodiment, patterned slot die deposition of the conductive adhesive ink 160 is also necessary, forming separate stripes aligned with the laser cuts in the back sheet. Each stripe corresponds to one of the cell ribbons, connected in series with neighboring ones.

[0056] In another preferred lamination embodiment, as depicted in FIG. 4B, conductive adhesive ink 160 may be deposited onto the back sheet 170 before the back sheet is roll-pressed onto the NP-HTL 150. Similar to the previous embodiment, it is crucial to adjust the moving velocity, injection rate, and temperature to attain optimal results. In this embodiment, laser patterning can be conducted after the conductive adhesive ink 160 is applied to the back sheet, thereby simplifying the P3 patterning process.

[0057] In addition to the mentioned embodiments, various similar lamination processes known to experts in the field can be implemented. Additionally, other experimental details and alternatives can be utilized during the lamination process. These include but are not limited to, employing alternative ink injection methods, laser processing for trimming and edge deletion, and the utilization of other continuous processes for back sheet lamination.

[0058] For lab-scale fabrication and testing, the aforementioned processes remain applicable. However, at a smaller scale, limitations arising from ink trapping beneath the back sheet are less severe, and there is no requirement for P1 , P2, or P3 laser patterning. Therefore, implementing lamination is comparatively easier compared to large-area modules. In the following example, the implementation of a lab-scale sample is presented:Example 1 : a lab-scale implementation

[0059] As an example, lab-scale perovskite solar cells with a layer’s structure of glass / fluorine-doped tin oxide (FTO) / compact TiC (c- TiC j / mesoporous TiC (mp- TiO2) / triple cation perovskite / CulnS2 / conductive adhesive ink / carbon foil were fabricated. To achieve this structure, FTO-coated glass substrates were patterned using Zn powder and diluted HCL The substrates were then cleaned sequentiallyusing diluted detergent, deionized water, HCI, and isopropanol for 15 minutes each. Before ETL deposition, the substrates were heated in a furnace at 500°C and then subjected to UV-Ozone treatment. For the c- TiC layer, an anhydrous ethanol solution of titanium isopropoxide (TTIP) and 0.2 M HCI was spin-coated onto the substrates at 2000 rpm for 30 seconds, followed by heating at 500°C for 1 hour. Next, a 20 nm particle paste of TiC in ethanol (1 :6.5 w / w) was deposited using spin-coating at 4000 rpm for 20 seconds to form the mp- TiC layer. This layer was dried at 100°C for 10 minutes and then placed in a furnace at 500°C for 30 minutes.

[0060] A triple-cation perovskite (Cso.o5(MAo.i7FAo.83)o.95Pb(lo.83Bro.i7)3 solution was prepared by dissolving Pbh, formamidinium iodide (FAI), PbBr2, methylammonium bromide (MABr), and Csl in DMF: DMSO (N, N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO) (4:1 v / v) solvent with molar concentrations of 1.1 :1 :0.2:0.2:0.05. The prepared solution was then spin-coated using a two-step program at 1000 rpm for 10 sec and 5000 rpm for 20 sec. 275 pl of chlorobenzene was poured on the substrates as the antisolvent 6 sec before the end of the second step. The samples were then annealed at 100°C for 1 h.

[0061] Next, as the hole- transport layer (HTL), a dispersion of CulnS2 nanoparticles in chloroform was deposited by spin-coating at 3000 rpm for 30 seconds, followed by annealing at 100°C for 10 minutes. To achieve the desired thickness, this procedure was repeated once more.

[0062] To prepare the conductive adhesive ink 160, the dispersion of CulnS2 nanoparticles in chloroform (the same dispersion used for the HTL) was mixed with a solution of polymethylmethacrylate (PMMA) in chloroform at a 3:1 volume ratio. Acetylene black powder, with a weight percentage between 0.5% and 2%, was added to the mixture and mixed until a uniform dispersion was achieved. The conductive adhesive ink 160, was then drop-cast onto a carbon foil. FIG. 5 shows an SEM image of this ink conductive adhesive ink 160, deposited on carbon foil after the chloroform solvent had dried. The ink-deposited carbon foil was then transferred using tweezers onto the prepared layers of the perovskite solar cell, ensuring that the conductive adhesive ink 160, was in contact with the holetransporting layer. Mild pressure was applied to the structure using lab slides and simple staple binder clips. After 5 minutes, the pressure was released, resulting in an intimate interfacial contact between the conductive layer and the hole-transporting layer. FIG. 1 illustrates a schematic diagram of the final perovskite solar cell.

[0063] FIG. 6 depicts the l-V measurement characteristics obtained for cells with Au back electrodes and laminated back electrodes. FIG. 7 represents the respective photovoltaic parameters. As shown in these figures, the perovskite solar cells with laminated back electrodes exhibited roughly the same photovoltaic parameters as the cells with Au back electrodes. The efficiency of the cell fabricated with the laminated carbon electrode is 17.16%, compared to 17.85% for the cell with the Au electrode. Furthermore, the perovskite solar cells with laminated electrodes had a higher open-circuit voltage compared to the cells with Au electrodes, and they exhibited less hysteresis, which is the discrepancy between photovoltaic parameters in forward and reverse scans.

[0064] This non-aqueous conductive adhesive ink 160, is compatible with perovskite. Laminating the back electrode using this ink is a simple procedure that does not require vacuum processing, high temperatures, or any complicated preparation processes. Importantly, the performance of the final fabricated perovskite solar cell is comparable to that of perovskite solar cells with expensive, vacuum-processed gold electrodes.

Claims

Claims

1. A method of manufacturing a hole-collecting electrode (200) for n-i-p perovskite solar cells, comprising steps of: a) deposing of a hole-transport layer (HTL) (150) comprising inorganic semiconductor nanoparticles, on top of a perovskite layer to form a substrate with the structure of sequential layers of glass (1 10), transparent conductive oxide (TCO) (120), electron transport layer (ETL) (130), perovskite (140), and HTL (150) comprising inorganic semiconductor nanoparticles (166), wherein, the semiconductor nanoparticles (166) are dispersed in a nonpolar solvent and applied atop the perovskite layer (140); b) providing a conductive adhesive ink (160), comprising: i. a non-polar solvent; ii. conductive filler (164); iii. Polymer binder (162); and iv. semiconductor nanoparticles (166), the same as the nanoparticles used in HTL (150); c) providing a foil of conductive back sheet; d) laser patterning the foil of the conductive back sheet; and e) applying a wet application to form a sandwich structure of HTL comprising inorganic semiconductor nanoparticles, conductive adhesive ink, and conductive back sheet, comprising steps of:I. applying the conductive adhesive ink (160) over the HTL (150) comprising inorganic semiconductor nanoparticles (166);II. continuously applying the foil of the back sheet (170) over the HTL (150) comprising inorganic semiconductor nanoparticles (166), using a roll-press; andIII. tuning the substrate’s (508) temperature to regulate solvent evaporation, leading to the dry incorporation of the conductive adhesive ink (160) between the HTL (150) comprising inorganicsemiconductor nanoparticles (166) and the conductive back sheet (170).

2. The method of claim 1 , wherein the HTL (150) comprising inorganic semiconductor nanoparticles (166) containing Cu (In, Ga) S2 nanoparticles.

3. The method of claim 2, wherein the Cu (In, Ga) S2 nanoparticles are capped with oleylamine ligands.

4. The method of claim 1 , wherein the HTL (150) comprising inorganic semiconductor nanoparticles (166) is deposited using ink deposition methods, including but not limited to spin coating, blade coating, and slotdie coating methods.

5. The method of claim 1 , wherein the non-polar solvent of conductive adhesive ink (160) is selected from a group consisting of chloroform, chlorobenzene, toluene, and xylene.

6. The method of claim 1 , wherein the polymer binder (162) of the conductive adhesive ink (160) is a perovskite passivating polymer.

7. The method of claim 6, wherein a perovskite passivating polymer is polymethylmethacrylate (PMMA).

8. The method of claim 1 , wherein the conductive adhesive ink (160) is injected using the slot die coating method.

9. The method of claim 1 , wherein the conductive back sheet (170) is patterned by laser or mechanically, prior to being applied onto the NP-HTL, to create cell ribbons in series connection, for optimal solar module device.

10. The method of claim 1 , wherein the conductive back sheet (170) is selected from the group consisting of carbon foils (CNTs, graphite or graphene), metal foils (Al, Ni, stainless steel), metal coated plastic films (aluminum, Ni, Cr or Ag Nanowires on plastic films) or conductive mesh (stainless steel, Ni, Ag, or Cu mesh).

11. A hole-collecting electrode (200) for n-i-p perovskite solar cells, comprising of:an HTL (150) containing inorganic semiconductor nanoparticles (166) laminated on top of a perovskite layer (140) using a conductive adhesive ink (160), wherein, the conductive adhesive ink (160) comprising of: a) a non-polar solvent; b) carbon black or acetylene black as a conductive filler (164); c) polymer binder (162); and d) semiconductor nanoparticles (166).

12. A hole-collecting electrode of claim 11 , wherein the HTL (150), comprising inorganic semiconductor nanoparticles (166) containing Cu (ln,Ga)S2 nanoparticles.

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