BISBENZIMIDAZOLIUM LIGANDS FOR DEFECT PASSIVATION AND PHOTOPHYSICAL MODULATION IN CsPbCl3 QUANTUM DOTS

Abstract

Cesium lead chloride (CsPbCl₃) quantum dots (QDs) possess excellent photophysical properties, including high photoluminescence quantum yield (PLQY), narrow emission, and tunable bandgap, yet their applications are limited by environmental instability and surface defects that promote non-radiative recombination. In this work, bisbenzimidazolium salts were employed as surface ligands to passivate defect states in hot-injection synthesized CsPbCl₃ QDs. Spectroscopic studies revealed that ligand passivation enhanced PLQY, narrowed emission linewidth, extended carrier lifetimes, and improved stability under ambient conditions. Tauc analysis further indicated a slight bandgap widening, consistent with defect suppression. These results demonstrate the effectiveness of bisbenzimidazolium salts in stabilizing perovskite QDs, offering a promising route for high-performance optoelectronic applications.