DOI: https://doi.org/10.29363/nanoge.hybridoe.2021.003
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.