Structural Stability, Tunable Electronic, and Optical Properties of XSi2N4/Cs2SnI6 (X = Cr, Mo, W) Heterostructures: First‐Principles Studies

Abstract

Novel optoelectronic and photovoltaic devices are promising, exploiting MoSi2N4‐based van der Waals (vdW) heterostructures. Herein, six vertical XSi2N4/Cs2SnI6 (X = Cr, Mo, W) heterostructures are constructed and the atomic structure, stability, and optoelectronic properties via first‐principles calculations are investigated. The results of binding energies indicate that XSi2N4/SnI4 is energetically favorable to be established compared to the XSi2N4/CsI. Computed charge density differences show that at the XSi2N4/SnI4 interface, there is no significant charge migration or rearrangement, making it unsuitable for use in charge transport devices. It is worth noticing that the built‐in electric field induced by electron transfer from CsI to the XSi2N4 layer prevents light‐induced electron and hole recombination, thereby improving carrier lifetime. Furthermore, the CrSi2N4/CsI heterostructure exhibits a wider range of visible light absorption, demonstrating its potential for applications in photoelectronic devices. The electronic and optical properties of XSi2N4/Cs2SnI6 can be tuned through element substitution. The findings could provide useful guidance for designing XSi2N4/Cs2SnI6 photoelectronic and photovoltaic devices.