Perovskite Qauntum Dot Surface Stabilization Using Nonpolar Solvent Dispersible Lewis-Base Ligand for Efficient and Stable Solar Cells

Thick and conductive perovskite quantum dot (PQD) solids for thin film solar cells can be fabricated via facile ligand exchange process. However, the conventional ligand exchange process that using ionic short-chain ligands and polar solvent inevitably deteriorate the PQDs surface, causing the surface trap sites such as uncoordinated Pb²⁺ sites. Thus, there is a limitation to boosting the performance of PQD solar cells using conventional ligand exchange process. Herein, we introduced novel surface stabilization strategy that can enhance the photovoltaic performance and operational stability of PQD solar cells using nonpolar solvent dispersible short-chain Lewis-base ligand. It is demonstrated that the triphenylphosphine oxide ligand can efficiently cover the uncoordinated Pb²⁺ sites via Lewis-base interaction and nonpolar solvent octane can preserve the surface components without additional desorption of surface ligands and ions. As a result, the surface stabilized PQD solar cells provide an enhanced power conversion efficiency of 15.4% together with durable device operational stability.