Intrinsic Interlayer Electric Field Induced Switched Regulatory Mechanisms of Photovoltaics and Photocatalysis in Z-scheme In2Se3/Sb Heterobilayer

Abstract

Two-dimensional (2D) van der Waals heterobilayers (vdWHs) with staggered band alignments are conducive to interlayer carrier separation, making them promising for solar energy conversion. However, These vdWHs exhibit two distinct carrier dynamics: type-II and Z-scheme. While type-II dynamics are well-studied, the Z-scheme mechanisms remain poorly understood. In this work, using In₂Se₃/Sb vdWH as an example, we explore how the interlayer electric field (E_int) promotes the Z-scheme carrier dynamics and its effects on photovoltaics (PVs) and photocatalysis (PCs). The results show that the spontaneous E_int in Z-scheme vdWHs, pointing from donor to acceptor, provides a simple way to distinguish them from type-II vdWHs. Besides verifying its intrinsic advantages in PCs, particularly in balancing the suitable band gap and efficient visible light absorption, the distinctive regulatory mechanisms are also demonstrated. In PCs, stronger E_int can enhance solar-to-hydrogen efficiency by facilitating the carrier separation, while in PVs, reversed photocurrent enhancements and red-shifts are observed. These findings not only underscore the importance of E_int directionality in Z-scheme vdWHs, but also provide insights for designing more efficient PV and PC systems.