Study On Large-area Perovskite Film Coating Technology And Perovskite Solar Modules

The power conversion efficiencies of perovskite solar cells(PSCs)have skyrocketed to 25.5%from the initial efficiency of 3.8%after decades of rapid development,which have exceeded other novel and some commercialized solar cells.However,the inferior efficiency of large-area device and stability issues are still existed.To solve above problems,by developing new deposition methods of large-area perovskite films,selecting perovskite materials with excellent intrinsic stability,designing novel module structure and developing reliable encapsulation technology,we achieve efficient and stable planar inverted structure perovskite solar modules(PSMs).The main contents and innovations are described as follows:(1)To solve the problem of uncontrollable formation of large-area methylammonium lead triiodide(MAPb I₃)perovskite film,a strategy used for blade coating MAPb I₃ thin film based on the solid-liquid reaction of lead iodate(HPb I₃)and methylamine(MA)is developed.On the one hand,the full Pb–I coordination structure of HPb I₃ reduces the formation of inherent defects;on the other hand,the anti-solvent treatment can promote the rapid nucleation to ensure a full coverage of the deposited film;Besides,the liquid intermediate phase of MAPb I₃·x MA can reform the film morphology,which is helpful to eliminate the pinholes.Finally,the crystallinity of perovskite film is further improved by the introduction of the NH₄Cl additive,and giving high-quality perovskite films over large area.Based on the fabricated perovskite film,planar inverted PSC(active area is 0.09 cm²)and series module(aperture area is 52.8 cm²)are fabricated with the device structure of FTO/Ni_0.8Mg_0.15Li_0.05O/MAPb I₃/C60/BCP/Cu.The resultant devices exhibit efficiencies of19.00%and 15.02%,respectively.The encapsulated PSM maintains 80%of its initial efficiency after aging for 700 h in ambient air under the white LED irradiation,maximum power point(MPP)tracking and the module temperature is 48°C.(2)To solve the problem of unclearness of the intrinsic stability of perovskites,the intrinsic stabilities of four perovskites,including MAPb I₃,FA_0.83MA_0.17Pb(I_0.83Br_0.17)₃(FA is formamidinium),Cs_0.05(FA_0.83MA_0.17)_0.95Pb(I_0.83Br_0.17)₃ and FA_0.85Cs_0.15Pb I_2.85Br_0.15,are studied under the combined stress of light(white LED array)and heat(65°C).By investigating the surface morphologies,structure and photoelectric properties changes of perovskite films before and after aging,the MA-free perovskite of FA_0.85Cs_0.15Pb I_2.85Br_0.15is demonstrated to possess optimal stability,which lays a foundation for fabricating highly efficient and stable PSMs over large area.(3)To solve the difficulty of coating large-area formamidinium cesium(FACs)perovskite film,the mechanism of adjusting crystal nucleation and growth of FACs perovskite with the N-methyl-2-pyrrolidinone solvent and diphenyl sulfoxide additive during the slot-die coating process is systematically investigated.By further anti-solvent treatment,a method of fabricating large-area FACs film is developed via slot-die coating technology.Based on the fabricated large-area FACs perovskite films with this method,planar inverted PSCs and parallel modules with the device structure of FTO/Ni_0.8Mg_0.15Li_0.05O/FA_0.83Cs_0.17Pb I_2.83Br_0.17/Li F/C60/BCP/Bi/Ag are fabricated.The highest efficiencies of PSCs and PSMs are 18.50%and 17.20%with an active area of 1 cm²and 20.77 cm²,respectively.The parallel module also gives a quasi-stabilized certified efficiency of 16.63%by a third-party photovoltaic certification center(Newport).To solve the problem of module stability,module encapsulation method is further developed based on aluminum oxide thin film deposited by atomic layer deposition,bynel sealant/cover glass,butyl rubber and aluminum tape.The encapsulated module maintains 97%of its initial efficiency after working under the day/night cycling aging with natural sunlight for 10000hours.The encapsulated module keeps 95%of its initial efficiency after aging under 1 sun equivalent white LED illumination in ambient air with MPP tracking and the module temperature is 50°C.