Highly Luminescent and Stable CsPbI₃ Perovskite Nanocrystals with Sodium Dodecyl Sulfate Ligand Passivation for Red-Light-Emitting Diodes

Abstract

CsPbI₃ perovskite nanocrystals (NCs) have recently emerged as promising materials for optoelectronic devices because of their superior properties. However, the poor stability of the CsPbI₃ NCs induced by easy ligand desorption represents a key issue limiting their practical applications. Herein, we report stable and highly luminescent black-phase CsPbI₃ NCs passivated by novel ligands of sodium dodecyl sulfate (SDS). Theoretical calculation results reveal a stronger adsorption energy of SDS molecules at the CsPbI₃ surface than that of commonly used oleic acid. As a result, the defect formation caused by the ligand loss during the purification process is greatly suppressed. The optimized SDS-CsPbI₃ NCs exhibit significantly reduced surface defects, much enhanced stability, and superior photoluminescence efficiency. The red perovskite light-emitting diodes based on the SDS-CsPbI₃ NCs demonstrate an external quantum efficiency of 8.4%, which shows a 4-fold improvement compared to the devices based on the oleic acid-modified CsPbI₃ NCs.