Antisolvent And Ion Doping To Enhance The Performance Of All-inorganic CsPbIBr₂ Perovskite Solar Cells

Since it was first reported in 2009,perovskite solar cells(PSCs)have attracted widespread attentions due to their high power conversion efficiencies(PCE)and low fabrication costs.After eleven years'rapidly development,the efficiency record of organic-inorganic hybrid perovskite solar cells has reached up to 25.5%,which is almost comparable to traditional crystalline silicon cells.However,in order to realize the potential commercialization applications,PSCs are still facing several challenges,mainly including the organic cations in organic-inorganic hybrid perovskite materials have poor stability to heat,water and ultraviolet light,resulting in the decomposition of the hybrid perovskite materials and the reduction of the corresponding cells'performances.In contrast,all-inorganic perovskite materials have obvious advantages in terms of thermal stability and light stability,especially the all-inorganic CsPbIBr₂perovskite,which demonstrates a balanceable feature for its acceptable bandgap,good phase stability and excellent thermal stability.At present,CsPbIBr₂ has some shortcomings such as the CsPbIBr₂ films prepared by one-step solution methods commonly have poor surface morphologies with many pinholes and low coverages.At the same time,its photovoltaic performances,especially the PCEs still needs to be further improved.Based on this,our subject focus on improving the quality of all-inorganic CsPbIBr₂ perovskite films and optimizing the photovoltaic performance of CsPbIBr₂ perovskite solar cells.The main research contents are as follows:1.Ethyl acetate(EA)is a good green anti-solvent,compared with conventional chlorobenzene(CB).These two anti-solvents were used to prepare CsPbIBr₂ films and fabricate a device structure of FTO/c-TiO₂/CsPbIBr₂/Carbon through one-step solution method.The results indicated that the CsPbIBr₂ film prepared by ethyl acetate exhibited an improved crystallinity,larger grain sizes and fewer grain boundaries,enhanced UV-visible light absorption intensity as well as reduced carrier non-radiative recombination.The CsPbIBr₂ device was prepared based on the green anti-solvent ethyl acetate,and its open circuit voltage(V_oc),short-circuit current density(J_sc),and fill factor(FF)were all improved,and the optimal efficiency reached 4.35%,which was 3.95%of the device prepared by chlorobenzene,an increase of 10%in efficiency.At the same time,the hysteresis of the device prepared by ethyl acetate was slightly improved,and showed better repeatability.2.Introduce cadmium ion(Cd²⁺)doping in the all-inorganic CsPbIBr₂ perovskite,improve the quality of CsPbIBr₂ film by optimizing the Cd²⁺doping concentrations,and fabricate cells devices based on a structure of FTO/Sn O₂/CsPbIBr₂/Carbon to investigate how Cd²⁺doping would influence the photovoltaic performance and stability of the devices.The research results demonstrated that,compared with the CsPbIBr₂PSCs without Cd²⁺doping,the efficiency of the CsPbIBr₂ PSCs increases from 4.36%to 6.79%when the Cd²⁺doping concentration was 0.5%,and its V_oc was1.19 V,and the J_sc was 9.76 m A/cm²,FF was 0.57.It was further discovered that the Cd²⁺doped device exhibited excellent stability in a high-humidity air environment(RH=55%).In addition,the entire device is fabricated under a low temperature condition(no more than 160?),which is beneficial for guiding the following researches on flexible substrates.