Facile Surface Stabilization Strategy for Efficient and Stable Perovskite Quantum Dot Solar Cells

Abstract

CsPbI3 PQD solids suffer from degradation in optoelectrical properties and film stability because of numerous trap sites on the PQD surface, which are generated after the ligand exchange process. Therefore, additional PQD surface stabilization strategy should be introduced which can improve the film quality of CsPbI3 PQD solids using covalent short-chain triphenylphosphine oxide (TPPO) ligands dissolved in an octane solvent. It is found that the TPPO ligand can bind with trap sites through Lewis-base interaction and the nonpolar solvent octane can preserve the PQD surface. As a result, the CsPbI3 PQD solids stabilized using the TPPO-octane solution showed reduced surface trap density than the control PQD solids. Consequently, CsPbI3 PQD solar cells which were stabilized using TPPO-octane solution provide a boosted power conversion efficiency and operational stability compared to control device.