Surface Ligand Management Aided by a Secondary Amine Enables Increased Synthesis Yield of CsPbI3 Perovskite Quantum Dots and High Photovoltaic Performance
Yao Wang,1 Jianyu Yuan,1,* Xuliang Zhang,1 Xufeng Ling,1 Bryon W. Larson,2 Qian Zhao,2 Yingguo Yang,3 Yao Shi,1 Joseph M. Luther2 and Wanli Ma1,*
1Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University, 199 Ren-Ai Road, Suzhou Industrial Park, Suzhou, Jiangsu 215123, P. R. China.
2Chemistry & Nanoscience Department, National Renewable Energy Laboratory, Golden, Colorado 80401, United States.
3Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204, P. R. China.
Lead halide perovskite quantum dots (PQDs) or more broadly, nanocrystals possess advantageous features for solution-processed photovoltaic devices. The nanocrystal surface ligands play a crucial role in the transport of photogenerated carriers and ultimately affect the overall performance of PQD solar cells. We have demonstrated significantly improved CsPbI3 PQD synthetic yield and solar cells performance through surface ligand management. The treatment of a secondary amine, di-n-propylamine (DPA), provides a mild and efficient approach to control the surfaces ligand density of PQDs, which has apparently different working mechanism compared to the previously reported surface treatment. Using an optimal DPA concentration, the treatment can simultaneously remove both long-chain insulating surface ligands of oleic acid and oleylamine, even for unpurified PQDs with high ligand density. As a result, the electrical coupling between PQDs is enhanced; leading to improved charge transport, reduced carrier recombination, and a high power conversion efficiency (PCE) approaching 15% for CsPbI3 PQD based solar cells. In addition, the production yield of CsPbI3 PQDs can be increased by a factor of 8. These results highlight the importance of developing new ligand-management strategies, specifically for emerging PQDs to achieve scalable and high-performance perovskite-based optoelectronic devices.