Polarization and mismatch controllable band alignment transitions and photocatalytic properties in CuInP2S6/MoTe2 heterostructures

Abstract

Understanding the physical mechanism of interface transport properties that affect hydrogen production is key for improving the performance of photocatalytic hydrogen generation reaction in two-dimensional (2D) van der Waals ferroelectric heterostructures with various band arrangements. Herein, four CuInP2S6 (CIPS)/MoTe2 heterostructures with three band alignment transitions are obtained by controlling polarization direction and interface mismatch. To study the influence of polarization reversal and the different band alignments on transport properties, an analytical model is established to clarify the interface charge separation and recombination induced by built-in electric fields in type-II and Z-scheme heterostructures. The results show that polarization reversal can enhance the interface electron mobility by more than two orders of magnitude, and interface Auger recombination can greatly enhance the lifetime of photogenerated carriers at relatively higher bands. Moreover, by involving the energy loss induced by the interface electric field scattering rate and Auger recombination rate, we find that the solar-to-hydrogen efficiency of CIPS/MoTe2 with Z-scheme heterostructure is much larger than that of type-II heterostructures. Our prediction provides a quantitative approach to deal with the photocatalytic properties from interface transport under various band alignments and may offer guidance to pursue multifunctional applications in 2D ferroelectric materials.