Study On Improveing The Performance Of Perovskite Solar Cells By Additive Process And Interface Modification

Organic-inorganic hybrid perovskite（Per SC）has become a promising semiconductor material because of its excellent photovoltaic properties.In order to realize the high photoelectric conversion efficiency（PCE）of Per SC,great efforts have been made to improve the device structure and optimize the calcium titanium deposit.In recent years,in single junction perovskite solar cells,PCE has increased from 3.8%reported for the first time to 25.7%certified,which has the potential to compete with commercial solar cells,but their instability and toxicity hinder their further commercial development.^[1-3]We solved the problems and challenges faced by perovskite solar cells by means of additive engineering,interface engineering and precursor composition regulation.The main research work is as follows:（1）In order to solve the problems of uncontrollable crystallization rate of narrow band gap Pb-Sn perovskite and easy oxidation of Sn²⁺,theβ-Diketone ligand material N,N,N’,N’-tetraphenylmalondiamide（TPMA）additive.Through the combination of experiment and theory,we come to the conclusion that TPMA has coordination with Pb²⁺and Sn²⁺,which can inhibit the migration of Pb²⁺and the oxidation of Sn²⁺.This strategy can effectively reduce the crystallization rate and obtain uniform perovskite films,so as to significantly reduce the defect density of states and improve the photoelectric conversion efficiency and stability by more than 20%.After 1000 hours of storage in a nitrogen filled glove box,the unpackaged Per SC retained 94%of its initial efficiency and lost only 8%of its life after 100 hours of continuous heating at 80°C.（2）In order to improve the poor wettability of PTAA and prepare high-quality perovskite films,we introduced Hexachlorocyclotriphosphazene（HCCP）,which has more phosphorus and nitrogen elements in the main chain and presents an alternating structure.The effect of its interlayer on the performance of p-i-n Per SC was studied.Compared with the standard parts without HCCP,the wettability of perovskite and HCCP on hydrophobic PTAA is improved and the V_oc is increased from 1.14 V to 1.20 V.Finally,Per SC containing HCCP was successfully prepared,and its photoelectric conversion efficiency was 20.65%.In terms of stability,the efficiency of devices without HCCP is reduced to about 70%of the original efficiency after continuous heating for 200 h.The PCE efficiency of the device with HCCP is only reduced by about 10%after 200 h heating.（3）Due to the solubility of materials such as Cs I and Cs Br,the preparation of perovskite films with high concentration and high thickness is limited.We propose to use new precursor materials to replace Cs I,Pb I₂ and Pb Br₂ with Cs Ac,Pb（Ac）₂,NH₄I and NH₄Br to prepare high-quality perovskite films.It is found that the introduction of acetate can promote the rapid crystallization of perovskite,making it possible to prepare dense and uniform high-quality perovskite films.Through the continuous optimization of precursor concentration and composition,we realized that the PCE of Cs Pb I₂Br Per SC prepared at 120℃reached 13.85%.