Affiliation:
1. Department School of Chemistry and Chemical Engineering Guangxi Key Laboratory of Electrochemical Energy Materials State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures Guangxi Colleges and Universities Key Laboratory of Applied Chemistry Technology and Resource Development. Guangxi University Nanning 530004 China
2. Department College of Chemistry and Resource Engineering Wuzhou University Wuzhou 543003 China
Abstract
AbstractThe preparation of high‐quality perovskite thin films with long‐term stability is the prerequisite for realizing efficient perovskite solar cells (PSCs). In this work, the effect of the bifunctional additive 1‐ethyl‐3‐methylimidazolium acetate (EMIMAc) ionic liquid on defect passivation in perovskite films was systematically investigated. Both theoretical simulations and experimental results reveal that EMIMAc has a strong coordination interaction with the undercoordinated Pb2+ through the lone electron pairs of carboxyl functional groups and the electron‐rich imidazole moieties, leading to a decreased deep defect density of MAPbI3 system. Besides, EMIMAc treatment realizes energy band alignment. As a result, the photoelectric conversion efficiency (PCE) of optimized PSCs reaches 17.07 %, and the filling factor (FF) exceeded 74.91 % which is the highest FF for hole transport layer (HTL)‐free carbon‐based MAPbI3 devices based on TiO2 electron transport layer. Moreover, the unencapsulated EMIMAc‐modified device maintains approximately 89 % of its initial PCE after 30 days, which demonstrates much better air stability than control devices. These results provide effective strategies for improving the efficiency and long‐term stability of HTL‐free carbon‐based PSCs (H‐C‐PSCs).
Funder
National Natural Science Foundation of China
Natural Science Foundation of Guangxi Zhuang Autonomous Region