High-efficiency And Stable Perovskite Solar Cell Precursor And Interface Optimization

So far organic-inorganic metal halide perovskite materials have attracted wide attention by the community due to their simple preparation and excellent photoelectric properties,such as tunable band gap,high absorption coefficient,and high carrier mobility.In recent years,NREL-certified power conversion efficiency(PCE)for PSCs has increased to 23.7%due to improvements in interface engineering,morphology control,device design and manufacturing.Two major issues faced by perovskite solar cells are:Low efficiency and poor stability.Based on the planar PSCs,focuses on improving the quality of perovskite films;optimizing the composition of perovskite precursor solution;applying a new material optimization interface,and preparing a highly efficient and stable CsPbI2Br PSCs.The main results of this dissertation are as follows:First,the bifunctional hydroxylamine hydrochloride was added into the MAPbl3 perovskite precursor solution as an additive.The highly efficient and stable MAPbI3 perovskite solar cells are successfully prepared by optimizing the solution concentration,annealing temperature and time.During the crystal growth process,the chloride ion in hydroxylamine hydrochloride can increase the grain size and reduce the grain boundary.At the same time,the hydroxyl group in the hydroxylamine hydrochloride and the iodide ion form a strong hydrogen bond,thereby passivating the interface of the perovskite films.The combination of these two effects can produce the PSCs with better photoelectric properties.Compared with the control sample,the power conversion efficiency of PSC with addictive is improved from 16.85%to 18.69%.The optimized device retains 95%of its initial efficiency after aging for 540 h in air(humidity-30%)or 75%after aging 20 h under 100?,which demonstrated that the hydroxylamine hydrochloride can improve the air and thermal stability of the PSCs effectively.Second,the TiO2 electron transport layer was modified by Nafion,and a high quality perovskite film was prepared.By optimizing the solution concentration,a PSC with good photoelectric performance was obtained,and the PCE was as high as 21.00%.It is found that the F-ions in Nafion solution can improve the crystallinity and surface morphology of FA0.85MA0.15PbI3 perovskite thin films.The FA0.85MA0.15PbI3 perovskite thin films modified with Nafion show the low defect density,less recombination and high electron extraction speed which resulted in the improved photovoltaic properties.Third,the inorganic CsPbI2Br perovskite thin film was successfully prepared at low temperature by using PbI2(DMSO)and PbBr2(DMSO)precursors.A stable and efficient inorganic PSCs was obtained on rigid or flexible substrates.The flexible device performance or solar cell efficiency is as high as 11.73%.After aging for 700 h in air,the optimized device can maintain about 70%of its initial efficiency.This study opens up a new avenue for preparing high performance flexible CsPbI2Br PSCs.