Charge Transfer Dynamics at the Interface of CsPbX3 Perovskite Nanocrystal-Acceptor Complexes: A Femtosecond Transient Absorption Spectroscopy Study

CsPbX3 (X = I-, Br-, Cl-) perovskite nanocrystals (PeNCs) are being explored extensively due to their impressive optoelectronic and photonic properties. Efficient harvest of photogenerated charge carriers from the particle is essential for photon-to-current conversion and enhancement of the performance of PeNC-based photovoltaic and optoelectronic applications. Since photoinduced charge transfer (CT) from the particle usually occurs on sub-picosecond to nanosecond timescales, time-resolved transient absorption (TA) spectroscopy is a powerful technique to investigate this transient dynamic photoinduced process. Herein reported investigations are reviewed, primarily employing femtosecond TA spectroscopy, of the CT process in CsPbX3 PeNCs. Based on the interpretation of TA spectral features and the basic model of CT dynamics, the concerns of CT rates or efficiency characterization in TA measurements, including multiple CT pathway effects, surface ligand effects, and hot charge carrier extraction are addressed. An elucidation of plasmon-induced hot electron transfer is also provided in CsPbX3 PeNC-noble metal heterostructures for their promising potential to contribute the development of CsPbX3 PeNC-based hot carrier devices. It is hoped that this review can provide deeper insights into the photovoltaic conversion in order to make the most of the CT process in CsPbX3 PeNCs.