Hole transfer dynamics between CsPbBr(3) PNCs and p-phenylene diisothiocyanate.

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. It 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 report the charge transfer dynamics between cesium lead bromide (CsPbBr) perovskite nanocrystals (PNCs) and -phenylene diisothiocyanate (PDNCS). The optical characteristics of the PNCs were investigated using UV-Vis absorption spectroscopy, steady-state photoluminescence (PL), and time-resolved photoluminescence spectroscopy. Femtosecond transient absorption spectroscopy (TAS), under varying excitation powers, was employed to probe charge transfer dynamics. A maximum transfer efficiency of approximately 57% was observed at an excitation energy of ∼1.39 = band gap. The PL quantum yield (PLQY) was found to be strongly dependent on the excitation wavelength. At a given quencher concentration, a linear increase of PLQY up to band edge excitation was observed, and a lower PLQY at high energy excitation has been explained due to higher hole transfer efficacy from PNCs to PDNCS.