Dynamic correlation between surface states and exciton in perovskite nanocrystals growth and ligand binding

Abstract

Colloidal lead halide perovskite (LHP) nanocrystals have attracted considerable interest in optoelectronics due to their exceptional photoelectric properties, yet quantifying the effect of nanocrystal surface states on exciton state alterations remains elusive, hindering understanding and modulation of exciton behavior. Here, we present a room-temperature synthesis strategy that decouples the supply pathways of ionized cesium and coordinated lead, enabling controlled nanocrystal growth over ∼20 min. Employing this methodology, we develop an in situ absorption-emission spectroscopy system to unveil dynamic association between nanocrystal growth kinetics and excitonic energy states, establishing a quantitative model for exciton physical characteristics. Further leveraging this dynamic correlation model, we probe the physical origin of the anomalous blue shifted absorption/emission spectra induced by benzenesulfonamide ligands. Our analysis reveals that ligand-mediated reduction of exciton binding energy constitutes the primary physical mechanism underlying the blue shifts. Urbach tail analysis confirms band edge disorder as the underlying mechanism. In situ spectroscopic monitoring and exciton state quantification enable the study of the dynamic photophysical properties of LHP nanocrystals.