Polarization-controllable interface charge transfer and photovoltaic properties in CuInP2S6/AsSBr heterostructures

Understanding charge behaviors at the interface of 2D van der Waals ferroelectric heterostructures is one of the important problems in fundamental physics and the key for designing high-performance optoelectronic devices. Herein, we develop an analytical model to study the interface charge separation and migration in CuInP2S6/AsSBr (CIPS/ASB) heterostructures. We reveal the influence of polarization reversal on the photovoltaic phenomenon using the tunable interface transport properties by modulating band alignment and built-in electric field. The results reveal that the interfacial electron mobility arises two orders of magnitude with the polarization reversal from up to down ward, which leads to the short circuit current and power conversion efficiency (PCE) enhanced by two times. Moreover, we find the thickness of CIPS and interface roughness play an important role in determining the optoelectronic properties as well, and suggest the optimal PCE can be obtained with ∼15 nm CIPS. Our method provides a general approach to deal with the optoelectronic properties and offers a guidance for improving the photovoltaic performances of ferroelectric-based nanodevices.