Hole transfer dynamics between CsPbBr3 PNC and p- phenylene diisothiocyanate

Abstract

Lead halide perovskites have rapidly emerged as promising materials for solar energy applications. A key factor in maximizing their photovoltaic efficiency is understanding the charge separation (electrons and holes) and their transfer across the interfaces. Charge transfer heavily depends on the choice of electron/hole acceptors and the search for suitable carrier acceptors is an active area of research. In this study, we examined the charge transfer dynamics between Cesium lead bromide (CsPbBr3) perovskite nanocrystals (PNCs) and p-phenylene diisothiocyanate (PDNCS). The optical characteristics of the CsPbBr3 PNCs were investigated using UV-Vis spectroscopy, steady-state photoluminescence (PL), and time-resolved PL measurements. Femtosecond transient absorption spectroscopy (TAS), under varying excitation powers, was employed to probe charge transfer dynamics. A maximum transfer efficiency of approximately 57% is observed at an excitation energy of ~1.39 Eg (Eg= band gap). PL quantum yield (PLQY) is found to be strongly dependent on the quencher (PDNCS) concentration and the excitation wavelength. At a given quencher concentration, a linear variation of PLQY up to near band edge excitation is observed.