In-situ ligand bonding management of CsPbI3 perovskite quantum dots enables high-performance photovoltaics and red light-emitting diodes
Junwei Shi1, Fangchao Li1, Yan Jin1, Cheng Liu1, Ben Cohen-Kleinstein2, Shuai Yuan1, Youyong Li1, Zhao-Kui Wang1, Jianyu Yuan1,* Wanli Ma1*
1Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, 199 Ren-Ai Road, Suzhou Industrial Park, Suzhou, Jiangsu 215123, P. R. China
2Waterloo Institute of Nanotechnology Engineering, University of Waterloo, Waterloo, ON, Canada N2L 3G1
Lead halide perovskite quantum dots (QDs) are promising materials for the next generation optoelectronic devices. Importantly, the bonding nature of QD capping ligands plays a crucial role in the resultant device performance. To fine-tuning the surface ligand towards high-performance devices, we first developed an in-situ passivation process for all-inorganic cesium lead iodide (CsPbI3) perovskite QDs by using a bi-functional ligand, namely L-phenylalanine (L-PHE). Through the addition of this ligand into the precursor solution during synthesis, the in-situ treated CsPbI3 QDs display significantly reduced surface states, increased vacancy formation energy, higher photoluminescence quantum yields, and much improved stability. Consequently, the L-PHE passivated CsPbI3 QDs enabled us to realize QD solar cells with an optimal efficiency of 14.62% and red light-emitting diodes (LEDs) with a highest external quantum efficiency (EQE) of 10.21%, respectively, demonstrating the great potential of ligand bonding management in improving the optoelectronic properties of solution-processed perovskite QDs.