Multi-Functional Conjugated Ligand Engineering for Perovskite Solar Cells and LEDs
Letian Dou a
a Purdue University, West Lafayette, IN, 47907, USA
Proceedings of International Online Conference on Hybrid Materials and Optoelectronic Devices (HYBRIDOE21)
Online, Spain, 2021 December 15th - 17th
Organizers: Jinwei Gao, Hua Yu, Dewei Zhao, Haizheng Zhong, Hairen Tan and Xueqing Xu
Invited Speaker, Letian Dou, presentation 003
Publication date: 3rd December 2021

Surface passivation is an effective way to boost the efficiency and stability of perovskite devices. However, a key challenge faced by most of the passivation strategies is reducing the interface charge recombination without imposing energy barriers to charge extraction. In this talk, I will present a novel multi-functional semiconducting organic ammonium cationic interface modifier inserted between the light-harvesting perovskite film and the hole transporting layer. We show that the conjugated cations can directly extract holes from perovskite efficiently, and simultaneously reduce interface non-radiative recombination. Together with improved energy level alignment and stabilized interface in device, we demonstrate a triple-cation mixed-halide medium-bandgap perovskite solar cell with an excellent power conversion efficiency of 22.06% (improved from 19.94%), and the suppressed ion migration and halide phase segregation, which lead to a long-term operational stability over 1000 hours. Using a similar concept, we achieved high performance red LEDs with external quantum efficiency over 15%. Our strategy provides a new practical method of interface engineering in perovskite solar cells and LEDs towards improved efficiency and stability.

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