Perovskite Termination-Dependent Charge Transport Behaviors of the CsPbI_3/Black Phosphorus van der Waals Heterostructure

Fundamental understanding of interfacial charge behaviors is of great significance for the optoelectronic and photovoltaic applications. However, the crucial roles of perovskite terminations in charge transport processes have not been completely clear. We investigate the charge transfer behaviors of the CsPbI_3/black phosphorus (BP) van der Waals heterostructure by using the density functional theory calculations with a self-energy correction. The calculations at the atomic level demonstrate the type-II band alignments of the CsPbI_3/BP heterostructure, which make electrons transfer from the perovskite side to monolayer BP. Moreover, the stronger interaction and narrower physical separation of the interfaces can lead to higher charge tunneling probabilities in the CsPbI_3/BP heterostructure. Due to different electron affinities, the PbI_2-terminated perovskite slab tends to collect electrons from the adjacent materials, whereas the CsI-termination prefers to inject electrons into transport materials. In addition, the interface coupling effect enhances the visible-light-region absorption of the CsPbI_3/BP heterostructure. This study highlights the importance of the perovskite termination in the charge transport processes and provides theoretical guidelines to develop high-performance photovoltaic and optoelectronic devices.