Encapsulation material for perovskite-based solar cells

Abstract

This invention relates to an encapsulation material for perovskite-based solar cells, the encapsulation material comprising a polymer matrix and a filler; the polymer matrix comprising polyisobutylene with a molecular weight between 30,000 Da and 800,000 Da, and the filler comprising a two-dimensional sheet; wherein the two-dimensional sheet is made of a material selected from the group consisting of: graphene, graphene oxide, reduced graphene oxide, fluorinated graphene, heteroatom-doped graphene, hexagonal boron nitride, metal chalcogenides, metal oxides, metal chalcogen halides, metal halides, phosphorus trichalcogenides, MXene, metal carbides, metal nitrides, layered hydroxides, alkaline earth metal silicides, alkaline earth metal bromides, alkaline earth metal germanides, alkaline earth metal tinides, layered perovskite, phosphorene, silylene, antimonene, germanene, boronene, tinene, bismuthene, and combinations thereof. A laminate comprising at least one layer made of the encapsulation material and a solar cell comprising the encapsulation material are also provided.

Description

Cross-reference to related applications

[0001] This patent application claims priority to Italian patent application No. 102023000018468, filed on September 8, 2023, the entire disclosure of which is incorporated herein by reference. Technical Field

[0002] This invention relates to an encapsulation material for perovskite-based solar cells and a laminate comprising the encapsulation material. Background Technology

[0003] Perovskite solar cells (PSCs) promise to revolutionize the photovoltaic ("PV") industry, thanks to their high power conversion efficiency (PCE) of up to 25.8% in single-junction configurations and up to 33.2% in series configurations, as well as their cost-effectiveness in materials and manufacturing processes.

[0004] However, in order to achieve a levelized cost of energy (LCoE) that can compete with the market-dominant crystalline silicon (c-Si) solar cells, it is necessary to improve the long-term stability of PSCs, especially when PSCs are assembled into modules, where further failures such as potential-induced degradation and reverse polarization effects may occur.

[0005] Generally speaking, the lifespan of a PSC is determined by both intrinsic factors (such as polymorphism, defects, lattice deformation, and ion migration) and extrinsic factors (such as humidity, oxygen, heat, and ultraviolet radiation).

[0006] The primary causes of degradation include structural transformations and phase separation in the perovskite thin film or charge transport layer (CTL), often accompanied by morphological changes. These mechanisms are typically triggered by ion migration and degassing of volatile molecules at perovskite grain boundaries and material interfaces. These effects are often exacerbated by the presence of lattice defects and / or deformations in the perovskite, as well as interfacial stresses caused by lattice mismatch and the coefficient of thermal expansion (TEC) of the battery material.

[0007] Some factors that may lead to the decomposition of perovskite are humidity and oxygen, which react with the perovskite light absorber. Water generates deprotonated organic cations through hydrogen bonding, thereby weakening the bond between the organic cations and the lead halide octahedra. Therefore, protons can be transferred via water molecules to halide ions (such as I₂). - The process generates volatile compounds (such as CH3NH2, HI, and PbI2). Simultaneously, oxygen can diffuse into the perovskite by occupying vacancies in the halides, and upon photoexcitation of the perovskite, charged superoxides can form. These processes trigger acid-base reactions with organic cations, leading to the formation of volatile compounds.

[0008] In this context, temperature changes, high temperatures, lighting, and the reverse polarization of the PSC all exacerbate the intrinsic decay effect, because photosensitive perovskite absorbers will undergo photodissociation if exposed to high temperatures.

[0009] To improve the intrinsic stability of perovskite ore, various strategies have been proposed, including engineering modification of the composition and size of perovskite ore, defect passivation, grain boundary modification, and material interface engineering.

[0010] Among strategies for improving stability, encapsulation is considered key to enabling PSCs and corresponding modules to be used outdoors for at least 20 years. However, encapsulation technologies known in the commercial photovoltaic field are not suitable for PSCs because they require temperatures exceeding the thermal stability of the perovskite and other functional layers of the PSC.

[0011] The main requirements for packaging systems suitable for PSCs are: 1) chemical inertness and chemical compatibility with the underlying battery materials (e.g., no release of degrading chemicals, such as ethylene vinyl acetate (EVA) and Surlyn, which release acetic acid and methacrylic acid, respectively); 2) low water vapor transmission rate (WVTR) (≤10). -4 gm -2 day -1 ) and low oxygen permeability (OTR) (≤10 -3 cm3 m -2 day -1 atm -1 1) Prevents moisture and oxygen from entering, while limiting the degassing of volatile substances; 2) Resists degradation processes caused by ultraviolet radiation (e.g., yellowing of PSC component materials and release of degradation products); 3) Provides thermal stability up to 85°C to withstand thermal stress (e.g., day / night thermal cycling) and processability at low temperatures (≤120°C) to ensure thermal stability compatibility with perovskite and common CTL materials; 4) Provides electrical insulation properties (i.e., resistivity >10 Ω·cm). 13 7) Mechanical properties, such as flexibility (i.e., low Young's modulus, preferably <20 MPa at 25°C) and adhesion (i.e., adhesive strength >0.1 MPa), to withstand thermomechanical stresses caused by daily temperature changes, as simulated by thermal cycling / shock aging tests.

[0012] To date, the combination of glass / leak-proof polymer / glass encapsulation has successfully achieved highly stable PSC, in which solar cells or solar modules are inserted between two glass plates (full coverage) using encapsulation polymer adhesive.

[0013] The encapsulating adhesives used include ethylene vinyl acetate (EVA), ionomers (Surlyn, Bynel, and Jurasol), polyisobutylene tape (PIB), polyolefin (POE), polyurethane (PU), and thermoplastic polyurethane (TPU). In addition, edge sealants made from butyl rubber-based tapes, UV-curable polymers, epoxy resins, silicone, and glass frits are typically used to fabricate stable devices.

[0014] Early reports indicated that small PSCs encapsulated with the aforementioned polymers could pass accelerated aging tests conforming to international standards (such as IEC-61215) and the International Summit on Organic and Hybrid Photovoltaic Stability (ISOS) protocol, such as (resistance) to damp heat (≥1000 h at 85°C, IEC 61215: relative humidity (RH) = 85%, ISOS-D-2: room temperature; PCE retention >80%) and / or thermal cycling (IEC 61215: ≥200 temperature cycles between -40°C and 85°C, other laboratory procedures: minimum temperature > -40°C; PCE retention >80%).

[0015] However, these results have not yet been fully validated in perovskite solar modules (PSMs), which prevents the commercialization of this type of solar cell.

[0016] A recent study (Wang, T. et al. Nat. Commu n. 14, 1342 (2023)) reported an efficient encapsulation strategy based on self-crosslinked fluorosilicone polymer gel, achieving PSC and 25 cm at room temperature. 2 PSM (effective area = 15.8 cm²) 2 Non-destructive encapsulation was performed. Using an unspecified epoxy edge sealant, the encapsulated PSM passed the IEC 61215 damp heat test (1000 h, PCE retention = 98%), but no other accelerated aging tests were conducted. Furthermore, the corresponding encapsulated PSC passed the IEC 61215 damp heat test (1000 h, PCE retention = 98%) and thermal cycling (220 cycles, PCE retention = 95%), although continuous exposure to light at 55±5°C for 1000 h resulted in a nearly 20% decrease in PCE.

[0017] Overall, there are very few reports on encapsulating PSMs using industrial methods (high-throughput), and apart from directly evaluating outdoor performance, systematic aging tests at an application-significant scale have not been conducted, which is insufficient for commercialization. Compared to traditional photovoltaic encapsulation materials, photovoltaic encapsulation materials used for PSMs must also consider thermal management functions due to the low thermal conductivity of perovskite absorbers. Furthermore, the high solubility product constant (Ksp) of perovskite byproducts is well-known (e.g., 4.4 × 10⁻⁶ for PbI₂). -9 M (11 orders of magnitude higher than PbS and PbSe) poses a risk of Pb release into the environment (approximately 40 μg / kWh), therefore, encapsulation materials must also possess Pb containment capabilities. Furthermore, low Young's modulus encapsulation materials are generally recommended for PSCs and PSMs to avoid delamination issues due to material TEC mismatch. Finally, during the assembly of the encapsulation material into cells as modules, leakage ("cell-to-module loss") should not occur due to the edge sealant occupying a large area; for a one-square-meter solar panel, the sealant width at the glass edges should be less than 1 cm. To date, most stability results have been collected with encapsulation areas even larger than the photoactive area, meaning these results still need to be validated in device configurations that ensure market-competitive LCoE.

[0018] Therefore, it is recognized in the art that there is a need to find new encapsulation materials that do not have the aforementioned drawbacks. In particular, there is a search for a technology that allows for the encapsulation of perovskite solar cells, a technology that is industrially available, does not use solvents, does not cause deformation or other mechanical stresses, and may not require the use of edge sealants.

[0019] Therefore, the object of the present invention is to provide an encapsulation material for perovskite solar cells that is industrially available, does not use solvents, does not cause deformation, and does not require the use of edge sealants. Summary of the Invention

[0020] This objective is achieved by the encapsulation material according to claim 1. A laminate according to claim 7 and a solar cell according to claim 8 are also provided.

[0021] According to one aspect of the present invention, an encapsulation material for perovskite-based solar cells is provided, the encapsulation material comprising a polymer matrix and a filler; the polymer matrix comprising polyisobutylene with a molecular weight between 30,000 Da and 800,000 Da, and the filler comprising two-dimensional (2D) sheets; wherein the 2D sheets are made of materials selected from the group consisting of: graphene, graphene oxide, reduced graphene oxide, fluorinated graphene, heteroatom-doped graphene, hexagonal boron nitride, metal chalcogenides, metal oxides, metal chalcogen halides, metal halides, phosphotrichalcogenides, MXene, metal carbides, metal nitrides, layered hydroxides, alkaline earth metal silicides, alkaline earth metal bromides, alkaline earth metal germanides, alkaline earth metal tinides, layered perovskites, phosphene, silylene, antimonene, germanene, boronene, stanene, bismuthene, and combinations thereof.

[0022] Advantageously, the PSM encapsulation material of the present invention provides an industrially available, solvent-free, and deformation-free encapsulation strategy based on viscoelastic (semi-solid) / high-viscosity (liquid) polyolefins. Thanks to the molecular weight of the selected PIB, the material exhibits a transition from semi-solid (high viscoelastic) to liquid (high-viscosity) as the temperature rises from -40°C to 85°C (the same temperature used for aging tests of photovoltaic devices according to internationally standardized tests).

[0023] In particular, the matrix can be homopolymer polyisobutylene (PIB) or a polyisobutylene copolymer that does not contain additives that cause polymer crosslinking.

[0024] PIB is known to be used as an encapsulation material for PSCs; however, the literature does not describe the use of homopolymers. This is because PIB is typically used in polymer blends (isobutylene-isoprene copolymers) and contains various additives (e.g., silanes, binders such as glyceryl rosin esters, layered minerals such as talc and kaolin, metal oxides, carbon black, and even molecular sieve desiccants). This leads to the crosslinking of PIB (by changing its molecular weight and transforming its physical state from semi-solid / liquid to solid), chemically bonding with the surface, improving anti-aging and waterproof properties, modulating rheological / mechanical properties, and controlling aesthetic characteristics (e.g., color). Therefore, the molecular weight of PIB encapsulation materials reported in the literature is greater than 80,000 Da, and such encapsulation materials exhibit a solid physical state.

[0025] Advantageously, compared with known encapsulation materials, two-dimensional (2D) inorganic fillers, especially hexagonal boron nitride (BN), offer advantages over other encapsulation materials. hThe presence of -BN) flakes (preferably produced on an industrial scale by a wet jet milling (WJM) process of natural powder as described and claimed in patent WO 2017089987) improves the adhesion, barrier properties and thermal management performance of the encapsulation material of the present invention.

[0026] At temperatures ranging from -45°C to 200°C, the Brinell viscosity of the encapsulation material at a rotation speed of 10 rpm is greater than 10,000 mPas.

[0027] In one embodiment, the 2D sheet is present in an amount of 0.1% to 30% by weight of the total weight of the encapsulation material, particularly in an amount of 0.5% to 10% by weight of the total weight of the encapsulation material.

[0028] PSM components encapsulated with the encapsulation material of the present invention (and, for example, based on a chemical composition Cs) after encapsulation and without the need for further sealing of the edges, are used in the encapsulation process. 0.08 FA 0.80 MA 0.12 Pb(I 0.88 Br 0.12 The perovskite (3) retains more than 80% of its initial PCE after thermal stress (e.g., ISOS-D-2 at 85°C, >1000 h), light immersion (ISOS-L-1, >1000 h), and accelerated aging tests (i.e., thermal shock (200 cycles of rapid temperature change between -40°C and +85°C) and humidity freezing tests (10 cycles of thermal shock with an intermediate stage of immersion in water at room temperature)).

[0029] According to a second aspect of the invention, a laminate is provided, comprising at least one layer made of the encapsulation material of the invention.

[0030] Finally, a perovskite-based solar cell incorporating the encapsulation material of the present invention is also provided. Attached Figure Description

[0031] The invention will be described in detail with reference to the accompanying drawings, which show only exemplary and non-exhaustive examples, wherein: Figure 1 This illustrates a) bare steel, PIB-coated steel, and encapsulation material coated with the present invention (PIB: ) in a corrosive environment. h -BN) Potentiodynamic anodic polarization measurement and corresponding Tafel analysis of steel; and b) Encapsulation material for PIB-coated steel and encapsulation material coated with the present invention (PIB: h The corrosion rate and corrosion inhibition efficiency of steel samples with -BN were analyzed. Figure 2 The images show water droplets on the thin film a) PIB, b) PIB: h-Photographs on the surface of BN, and c) for PIB and PIB: h -Water contact angle data measured for BN thin films; Figure 3 The use of PIB or PIB is shown: h The highest temperature measured over time for the glass pairs laminated together with BN encapsulating adhesive was first heated to 85°C (t=0 s) and then transferred to an aluminum platform at 25°C. Figure 4 The diagram shows the laser ablation process (P1-P2-P3) used to determine the PSM layout and a schematic diagram of the layered structure of the module. Figure 5 Temperature profiles for a representative thermal shock test of PSM are shown. Figure 6 Temperature profiles and environmental exposure conditions for a representative humidity-freezing test of PSM are shown. Figure 7 This shows a) IEC 61215 thermal cycling and Figure 5 A comparison of the temperature curves from the thermal shock tests; b) an enlarged view of the temperature curves shown in Figure a), with accompanying diagrams. Figure 5 Evidence of the first cycle of thermal shock testing; c) IEC 61215 testing and Figure 6 A comparison between the temperature and UR curves of the humidity freezing test; d) a magnified view of the temperature and other environmental conditions (immersion in water or exposure to ambient air) shown in Figure a), with accompanying diagrams. Figure 6 Evidence for the first cycle of the humidity freezing test includes the step of immersion in water. Detailed Implementation

[0032] The present invention will now be illustrated by some embodiments, but these embodiments are not intended to limit the scope of the invention.

[0033] Example To encapsulate the PSC and PSM, two types of encapsulation materials were prepared, as described in the Methods section below. Specifically, the first encapsulation material was PIB, a transparent, high-viscosity liquid at room temperature, while the second encapsulation material was PIB and 2D hexagonal boron nitride (PIB). h -BN) opaque complex of sheet-like material (hereinafter referred to as PIB: h -BN), the latter through the h -BN crystals were prepared by wet jet milling. Although PIB possesses amorphous and semi-solid / liquid properties (in the temperature range of -40℃ / +85℃), its molecular chains are stacked together, resulting in excellent barrier properties. Furthermore, the resistivity of PIB is approximately 10⁻⁶. 16 Ω cm, higher than the resistivity of EVA (10 13Ω cm to 10 15 Ω cm), which leads to potential degradation-induced inhibitory performance. Furthermore, 2D h Incorporating BN flakes into a PIB matrix is ​​an effective strategy to improve the barrier properties of pure polymers against water (and therefore moisture) and other corrosive substances. 2D h The barrier properties of -BN are generally attributed to its high specific surface area (monolayer). h -BN is 1488 m 2 g -1 The morphology and hydrophobic properties of ). Furthermore, h The dense delocalized electron cloud of overlapping π orbitals in -BN represents a physical barrier preventing the penetration of molecules or ions, thus resulting in atomic impermeability. Furthermore, 2D... h -BN sheets exhibit high thermal conductivity (e.g., for atomic monolayers) h -BN is >700 W m -1 K -1 For those with several or more atomic layers h -BN is >100 W m -1 K -1 This improves the thermal management performance of polymers when used as additives.

[0034] method Material High-viscosity PIB at room temperature (Bruch's viscosity >100,000 mPas at 10 rpm at <120°C) (LMW-80, average molecular weight 95,000) is supplied by TER Chemicals. h -BN powder is supplied by Alfa Aesar. Unless otherwise stated, all chemicals should be used as is upon receipt.

[0035] Preparation of encapsulation materials To produce PIB homopolymer encapsulation material, PIB was first dissolved in toluene at a PIB:toluene weight ratio of 1:1.5, and the solution was vigorously stirred at 800 rpm and 80°C (500 rpm) for 12 h until a homogeneous solution (hereinafter referred to as PIB resin) was obtained. To produce PIB: h -BN encapsulation material, produced using BeDimensional SpA's (WO2017089987) patented wet jet milling (WJM) method, has few layers. h -BN flakes. In the experiment, N-methyl-2-pyrrolidone (NMP) and h -A mixture of BN crystals (NMP: h-BN weight ratio 98:2) is pressurized into two jet streams, which collide in the nozzle to generate shear force to achieve the grinding mechanism. 2D produced by WJM is dried using a dryer. h -BN plate-like dispersion. Finally, the obtained 2D h -BN flakes were added to the PIB solution, and then mixed at 1000 rpm for 5 minutes using a planetary centrifuge (Thinky ARE-250 mixer / deaerator) to obtain PIB: h -BN composite material (hereinafter referred to as PIB: h -BN resin), wherein h-BN accounts for 5% of the total weight of the encapsulant (excluding solvent). Previously tested electrochemically according to ASTM G5-14, ASTM G59-97, ASTM G61-86 and ASTM G106-89 standards. h -BN content was optimized to maximize incorporation. h Barrier properties of the PIB encapsulation material. Electrochemical characterization was performed on samples produced using PIB LMW-80. For the production of the encapsulation material, PIB resin and PIB were used: h -BN resin was deposited by spreading on a 1 mm thick glass substrate for glass / pressure-resistant polymer / glass encapsulation of PSCs and PSMs. The resulting film was dried at room temperature for 1 hour, then dried at 60°C for 15 hours to evaporate residual solvent. The resulting homopolymer PIB or PIB after solvent evaporation was measured using a Trotec BB20 thickness measurement system. h - The thickness of the BN film is between 600 µm and 700 µm (for these measurements, the encapsulation film is deposited on the metal substrate using the same procedure and parameters as the glass coating).

[0036] Characterization of encapsulation materials PIB and PIB were measured using an OSBILA L2004A1 contact angle goniometer: h - Water contact angle of the PIB film, imagine a 10 μL water droplet deposited on the sample. The measured contact angle of the PIB film is 88.3° ± 0.4°. (The remaining text appears to be incomplete and possibly contains errors.) h The contact angle of the -BN film is 97.9° ± 0.4°. Figure 2 ).

[0037] Electrochemical measurements were performed to evaluate the barrier properties of the encapsulant.

[0038] Electrochemical measurements were performed using a BioLogic VMP3 multichannel potentiostat in a 1 L three-electrode electrochemical cell at room temperature in 3.5 wt% NaCl aqueous solution, following the procedure described in ASTM G5-14. A KCl-saturated Ag / AgCl REF201 RedRod (Biologic) radiation reference electrode was used as the reference electrode, and a graphite rod as the counter electrode. The standard components of the working electrode consisted of PIB or PIB-coated electrodes. h - A cylindrical sample consisting of a structural steel base (S355) of -BN, drilled and tapped with 3-48 UNC threads, and screwed onto a support rod. PIB or PIB: h -BN films were prepared by depositing the appropriate resin through spreading, followed by drying at room temperature for 1 hour and then at 60°C for 15 hours to evaporate residual solvent. After solvent evaporation, the obtained PIB or PIB was measured using a Trotec BB20 magnetic induction measurement system. h The -BN film thickness is approximately 60 µm. Teflon compression gaskets ensure a leak-free seal. Open-circuit voltage is monitored for 30 minutes, and then the corrosion properties of the coating are analyzed according to ASTM G5-14 standards using potentiodynamic anodic polarization measurements and relative Tafel analysis to determine the corrosion current of the metal (i). corr ) and corrosion potential. According to Faraday's law, through i corr Calculate the corrosion rate of the sample, i.e.:

[0039] In the formula: CR is the corrosion rate (unit: mm yr). -1 K is a constant with a value of 3.27 × 10⁻⁶. -3 W eq The equivalent of iron in the ferrous compound (27.9 g eq) -1 ), i corr Corrosion current density (unit: μA cm⁻¹) -2 D is the density of steel (7.85 g / cm³). -3 The corrosion rate of the sample is determined by i. corr The corrosion inhibition efficiency (η) of the composite was calculated. p ) from i corr Begin calculating using the following formula:

[0040] In the formula: i 0 corr and i corr These are the corrosion current densities with and without inhibitors, respectively.

[0041] Figure 1 a shows PIB or PIB immersed in a corrosive environment (3.5 wt% NaCl aqueous solution): h Potentiodynamic anodic polarization measurements and corresponding Tafel analyses were performed on -BN coated steel (results for bare steel are shown for comparison purposes). These experiments were conducted according to ASTM G5-14 and ASTM G59-97 standards. The results show that PIB and PIB: h -BN films possess barrier properties, reducing the corrosion rate from 7.3 × 10⁻⁶ for structural steel. -1 The average value of PIB-coated steel was reduced to 1.5 × 10⁻⁶. -1 mm yr -1 And PIB: h The average value of BN-coated steel is 1.7 × 10⁻⁶. -4 mm yr -1 ( Figure 1 a). It is worth noting that adding 2D to the PIB matrix h -BN flakes improve the repeatability of the corrosion protection performance of PIB films. Overall, the data show that compared to homopolymer PIB (average corrosion inhibition efficiency = 79.53%), PIB: h -BN film (average corrosion inhibition efficiency = 99.97%) has excellent barrier properties. Figure 1 b). This effect is attributed to 2D. h The presence of -BN flakes results in higher hydrophobicity (PIB and PIB: h The water contact angles of the -BN films were 88.3°±0.4° and 97.9°±0.4°, respectively. Figure 2 ).

[0042] PIB: h The superior barrier properties of -BN can also be verified by a calcium corrosion test (“Ca test”), which analyzes calcium corrosion by measuring the strength of the calcium film encapsulated by the glass / pressure-resistant polymer package (similar to the method proposed for PSC and PSM (full coverage)). In this configuration, moisture cannot penetrate the glass (therefore, moisture enters laterally from the edge of the device through the encapsulation material).

[0043] By examining the glass / PIB: h The WVTR calculated by electrical measurement of the Ca film encapsulated in the -BN system is less than 5 × 10⁻⁶. -5 gm -2 d -1 .

[0044] Glass / PIB / glass and glass / PIB were monitored using a thermal imager (A655sc, FLIR) located approximately 50 cm from the sample surface: hThe thermal management performance of the encapsulation material was evaluated based on the highest temperature of the BN / glass system (area = 5.6 cm × 5.6 cm). PSC and PSM encapsulation samples were prepared using a lamination process. Samples were heated to 90°C in a covered hot plate and then transferred to an Al platform at 25°C. The system temperature was monitored during cooling. The thermal imager was controlled by FLIR (Temperature FLIRResearchIR Max software), which was also used to process the temperature data. Figure 3 As shown, compared with the system based on pure homopolymer PIB, 2D h The presence of -BN flakes improves the system's heat dissipation capacity, reducing the time to reach 30°C by 11.2%.

[0045] Manufacturing of perovskite solar cells and modules Mesoscopic PSC The fabrication process for PSCs is known in the literature (see, for example, Mariani et al., ACS Appl. Mater. Interfaces 2021, 13, 19, 22368–22380 and Vesce et al., RRL Solar, 2022, vol. 6, number 7). A common configuration is a layered structure of the following type: transparent conductive oxide (TCO) / electron transport layer (ETL) / perovskite / passivation layer (e.g., phenylethyl ammonium iodide, PEAI) / hole transport layer / back electrode (e.g., gold or carbon electrode, including graphene-based electrodes). The ETL can be mesoporous (e.g., mesoporous TiO2) or dense (e.g., dense TiO2 or SnO2), which is why the resulting PSCs are referred to as mesoporous and planar, respectively. Mesoporous PSCs are sometimes fabricated by coupling a dense ETL layer with a second mesoporous ETL layer (e.g., dense TiO2 + mesoporous TiO2).

[0046] A representative example of a perovskite absorbent is Cs. 0.08 FA 0.80 MA 0.12 Pb(I 0.88 Br 0.12 )3, which can be easily obtained by using well-known precursors and relative proportions in the literature (see, for example, Mariani et al., ACS Appl. Mater. Interfaces 2021, 13, 19, 22368–22380 and Vesce et al., RRL Solar, 2022, vol. 6, number 7, 2101095).

[0047] Mesoscopic PSM The manufacturing process of PSM is similar to that of PSC, except for the amount of solution poured onto the substrate and three additional laser ablation processes (P1-P2-P3, see below) used to define the layout of the tandemly connected PSCs. Figure 4 As described in the literature (Castriotta et al., Advanced Energy Materials, 2022, vol. 12, issue 12, 2103420).

[0048] Lamination of perovskite solar cells and modules PIB and PIB: h -BN encapsulant can be applied to PSCs and PSMs via low-temperature (≤120°C) lamination processes, such as multiphase lamination at 90°C and differential pressure using an automated dual-chamber laminator for solar panels. This automated dual-chamber laminator is equipped with a cooling system to ensure high repeatability of the lamination process and reduce the time the material is exposed to temperatures that cause degradation. In experiments, the entire surface of the device was covered with PIB or PIB-coated material. h -BN encapsulation glass ensures glass / pressure-resistant polymer / glass encapsulation (full coverage) for both PSC and PSM. The assembled laminate is inserted into the lower chamber of the laminator using the pressure difference between the upper and lower chambers. After sealing the laminator, the lamination process is performed. For example, the laminator chambers are evacuated under a moderate vacuum (approximately 1 mbar pressure) while the laminate is heated from room temperature to 50°C, for example, over a time interval between 200 and 250 seconds (e.g., approximately 7°C min). -1 Then, the upper chamber is inflated to apply a final pressure of, for example, 30 mbar to the upper portion of the substrate. The laminate is then heated to, for example, 400 s to 600 s (e.g., 5°C min). -1 The temperature is increased from 50°C to between 80°C and 120°C over a time interval, and maintained at the final temperature for a period of time, such as between 500 s and 700 s. Subsequently, the temperature of the laminate is reduced to 50°C and the chamber pressure is restored to 1000 mbar, thereby turning on the laminator and completing the device output.

[0049] Device characterization The ISOS-L-1 and ISOS-D-2 tests are described in the literature (Khenkin et al., Nature Energy vol.5, p. 35–49 (2020)). An example of thermal shock testing involves oscillating the sample temperature between -40°C and +85°C with abrupt temperature changes (from room temperature to +85°C and vice versa, from room temperature to -40°C and vice versa, see [reference]). Figure 5 This can be performed using [the method described in the original text]. An example of a humidity-freezing test (modified according to the protocol reported in IEC 61215) can be performed after 200 thermal shock cycles, including 10 thermal shock cycles between -40°C and +85°C, each cycle beginning with immersion in water at room temperature (see [link to relevant documentation]). Figure 6 ).

[0050] Inductively coupled plasma optical emission spectroscopy (ICP-OES) measurements can be performed, for example, using a ThermoFisher iCAP 7600 DUO spectrometer, to measure the Pb loss of PSCs and PSMs immersed in water by sampling the aqueous solution over time.

[0051] Preliminary assessment of encapsulation materials in PSC PIB: h -BN encapsulation material was selected due to its superior barrier properties compared to PIB, and preliminary testing was conducted in a nip mesoscopic PSC configuration. PIB: h -BN encapsulation material was coated using a high-speed lamination process (total duration <45 minutes) compatible with mass production. Experimental evidence shows that the lamination process has little impact on the overall performance of the battery (absolute PCE decrease <1%). During ISOS-D-1 testing, the PSC maintained its performance, confirming its stability. After >1000 hours of ISOS-D-2 and ISOS-L-1 testing, the unencapsulated battery rapidly degraded, T... 80 (The time required for the PCE to drop to 80% of its initial value, as defined, is typically less than 100 h in the ISOS-D-2 test and less than 10 h in the ISOS-L-1 test, and this also applies to Cs-based perovskite absorbers.) 0.08 FA 0.80 MA 0.12 Pb(I 0.88 Br 0.12 The PSC of 3. In contrast, the encapsulated battery exhibits T without the use of edge sealant. 80 >1000 h. PIB: h The effectiveness of the -BN encapsulant has also been demonstrated on planar nip PSCs, for example, PSCs based on dense SnO2 ETL deposited at low temperatures, with T values ​​reported during ISOS-D-2 testing.80 It is approximately 2000 h, while those unpackaged PSCs typically show a lower T of 700 h. 80 .

[0052] Validation of encapsulation materials in PSM Subsequently, as described in the literature (e.g., Vesce, L. et al., Sol. RRL 5, 2100073 (2021)), in nip mesoscopic PSM, for PIB and PIB: h -BN encapsulation material was evaluated. The encapsulation material was applied according to the lamination scheme described for PSC, ensuring complete coverage of the porous layers of the module structure. Similar to PSC, edge sealants do not need to be combined with the encapsulant of this invention. As with cells, the encapsulation process has little impact on the overall performance of the module (absolute PCE decrease <1%). During the 240-hour ISOS-D-1 test, PSM performance remained unchanged (absolute PCE decrease <1%). During the ISOS-D-2 and ISOS-L-1 tests, the unencapsulated PSM degraded rapidly, typically showing T0... 80 <100 h and <10 h. In contrast, packaged PSMs typically show T 80 >1000 h.

[0053] Thermal shock testing (between -40°C and +85°C) was performed on the packaged PSM, followed by an improved humidity-freezing test, confirming the effectiveness of PIB. h -BN encapsulant provides reliability and barrier function. Figure 5 and Figure 6 Temperature profiles and environmental conditions (e.g., immersion in water and exposure to air) for representative thermal shock and humidity freezing tests are shown. Figure 7 This section describes a comparison with the thermal change and humidity-freezing tests of the IEC 61215 standard. In accelerated aging stress, sudden temperature changes cause intense thermomechanical stress due to the thermal expansion and contraction of materials with different TECs, severely impairing the adhesion between layers and the reliability of electrical interconnects. PIB was used. h -BN packaging material's PSM can withstand at least 200 thermal shock cycles, retaining >80% of the initial PCE. PIB: h -BN packaging materials outperform PIB packaging materials, indicating the superior performance of 2D packaging materials. h -BN flakes, used as a thermally conductive additive, are an effective strategy to improve the overall thermal management performance of PSMs by integrating passive cooling into the packaging system. This is consistent with the thermal properties measured for the packaging material of this invention. Figure 3 Using PIB: hThe -BN packaged PSM, after humidity-freezing testing, maintained >85% of its initial PCE after 10 cycles. PIB was evaluated by measuring Pb release from the packaged PSM immersed in water using inductively coupled plasma optical emission spectrometry (ICP-OES). h -BN encapsulation material effectively protects PSM from external factors. Upon immersion in water, unencapsulated PSM rapidly degrades, exhibiting yellowing associated with perovskite decomposition into PbI2. This is due to its high solubility (340 mg / L). -1 Solubility product constant = 4.4 × 10 -9 PbI2 dissolves rapidly in water (M), and the detected Pb loss (>60 µg cm⁻¹ after 24 hours) was [not specified]. -2 The Pb content is consistent with that in perovskites, typically around 0.1 gm. -2 Up to 1 gm -2 Between. Compared to the unencapsulated device, the perovskite in the encapsulated PSM retained its initial color, thus preserving the perovskite phase. As a result, Pb leakage was significantly suppressed to below 1 µg cm⁻¹ after 24 hours. -2 (Low Pb water contamination may be related to perovskite residues near the edge of the encapsulant, rather than perovskite degradation on the active region of the PSM).

[0054] in conclusion The viscoelastic / high-viscosity liquid nature of PIB inherently limits the thermomechanical stresses caused by temperature gradients that occur during the encapsulation process and accelerated aging stresses. (2D) h -BN flakes are incorporated into the PIB matrix to improve the barrier properties and thermal management properties of PIB homopolymers.

[0055] Without using edge sealant, the present invention, based on PIB and 2D... h -BN sheet encapsulation material encapsulated PSCs and PSMs withstood multiple accelerated aging tests, including ISOS-D1 (>20 h), ISOS-D2 (>1000 h), ISOS-L1 (>1000 h), as well as custom thermal shock tests (≥200 cycles) and improved humidity-freezing tests (≥10 cycles), maintaining more than 80% of their initial PCE.

[0056] The above results represent a significant step forward in achieving long-term stable PSMs by combining high-speed processability, compatibility with eCTL perovskites, barrier properties, adhesion, thermal stability, and light stability with a semi-solid / liquid encapsulation material compatible with low-temperature and low-cost lamination processes, without the need for advanced perovskite formulations with high internal stability or edge-specific sealants.

Claims

1. An encapsulant material for a perovskite-based solar cell, the encapsulant material comprising a polymeric matrix and a filler, the polymeric matrix comprising polyisobutylene having a molecular weight between 30 000 Da and 800 000 Da, the filler comprising two-dimensional platelets, wherein, The two-dimensional sheet is made of materials selected from the group consisting of: graphene, graphene oxide, reduced graphene oxide, fluorinated graphene, heteroatom-doped graphene, hexagonal boron nitride, metal chalcogenides, metal oxides, metal chalcogen halides, metal halides, phosphorus trichalcogenides, MXenes, metal carbides, metal nitrides, layered hydroxides, alkaline earth metal silicides, alkaline earth metal bromides, alkaline earth metal germanides, alkaline earth metal tinides, layered perovskites, phosphine, silylene, antimonyene, germanene, boronene, tinene, bismuthene, and combinations thereof.

2. The encapsulant material of claim 1, wherein, The polymer matrix is ​​made of homopolymer polyisobutylene.

3. The encapsulant material of claim 1, wherein, The two-dimensional sheet is made of hexagonal boron nitride.

4. The encapsulant material of claim 1, wherein, The two-dimensional sheet is present in an amount of 0.1% to 30% by weight of the total weight of the encapsulation material.

5. The encapsulant material of claim 4, wherein, The two-dimensional sheet is present in an amount of 0.5% to 10% by weight of the total weight of the encapsulant.

6. The encapsulant material of claim 1, wherein, Under temperature conditions between -45°C and 200°C, the encapsulation material has a Brinell viscosity greater than 10,000 mPas at 10 rpm.

7. A laminate comprising at least one layer made of an encapsulation material according to any one of claims 1 to 6.

8. A perovskite-based solar cell comprising the encapsulation material according to any one of claims 1 to 6.

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