High-Efficiency All-Inorganic Perovskite Solar Cells

Inorganic mixed-halide CsPbX3-based perovskite solar cells(PeSCs)are emerging as one of the most promising types of PeSCs on account of their thermostability compared to organic-inorganic hybrid counterparts.However,dissatisfactory device performance and high processing temperature impede their development for viable applications.To solve the problem of low-efficiency of all-inorganic PeSCs,this thesis focuses on the morphology control and energy level modification for perovskite films to improve the performance of all-inorganic perovskite cells,which includes the following aspects.Firstly,for suppressing the loss of photo-generated carriers in the perovskite film,we used a two-step gradient thermal annealing method to realize precise control of a-CsPbI2Br growth,contributing to a high-quality perovskite film.Therefore,the electrons and holes will not be bound by defect states.PeSCs based on this CsPbI2Br film achieved a champion PCE of 12.68%Secondly,to further suppress the loss of photo-generated carriers at the interface of the functional layer and improve the efficiency of all-inorganic PeSCs,a facile route is presented for tuning the energy levels and electrical properties of sol-gel-derived ZnO electron-transporting material(ETM)via doping a classical alkali metal carbonate,Cs2CO3.Compared to bare ZnO,the Cs2CO3-doped ZnO possesses more favorable interface energetics in contact with the CsPbI2Br perovskite layer,which can reduce the ohmic loss to a negligible level.The optimized PeSCs achieved an improved open-circuit voltage of 1.28 V,together with an increase in fill factor and short-circuit current.The optimized power conversion efficiencies of 16.42%is realized on rigid glass substrate,which is one of the highest efficiencies reported for all-inorganic PeSCs to date.A high thermostability can be simultaneously obtained via defect passivation at the Cs2CO3-doped ZnO/CsPbI2Br interface,and 81%of the initial efficiency is retained after aging for 200 h at 85℃.Finally,we fabricated the flexible all-inorganic PeSCs by using PET substrates with spin-coated silver nanowires(Ag NWs)as on flexible electrodes,instead of traditional ITO electrode.The transparent electrodes show good conductivity and high transmittance Eventually,flexible PeSCs on plastics achieved a power conversion efficiency of 14.82%.Moreover,the flexible PeSCs using this composite electrode retained 81%of their initial efficiency after 1000 bending cycles at a radius of 8 mm,which exhibits excellent bending resistance.This thesis proposed a carrier recombination suppression strategy based on morphology control and energy level modification for all-inorganic PeSCs.In addition,an efficient integration process for rigid and flexible devices was developed.Moreover,it provides a method for preparing flexible all-inorganic PeSCs and the experimental guidance for future research.