Effect of temperature and electric field on interfacial charge transfer and band-edge alignment in MXene-halide perovskite heterostructures

The interfacial charge transfer and band-edge alignment coupled with strong visible light absorption in the heterostructure is a fundamental tuning criterion for both photovoltaic and photocatalytic efficiencies. We have envisaged how both criteria evolve under the influence of electric field and temperature in a novel van der Waals (vdW) heterostructure composed of the all-inorganic perovskite ${\mathrm{CsSnI}}_{3}$ and the two-dimensional (2D) MXene ${\mathrm{Zr}}_{2}{\mathrm{CO}}_{2}$. Using density functional theory (DFT), we have systematically investigated the structural, electronic, and optical responses of the ${\mathrm{CsSnI}}_{3}\text{\ensuremath{-}}{\mathrm{Zr}}_{2}{\mathrm{CO}}_{2}$ heterostructure under these external perturbations. Our results reveal that controlled tuning of thermal and electric field conditions effectively modulates the band alignment, enabling enhanced charge separation and extraction, crucial for optimizing photovoltaic performance. Beyond photovoltaics, we demonstrate that the synergistic influence of electric field and temperature promotes favorable band-edge positions relative to water redox potentials, alongside strong visible-light absorption, leading to a theoretical solar-to-hydrogen conversion efficiency approaching 30%. These insights underscore the promise of 2D perovskite-MXene van der Waals heterostructures as multifunctional materials for efficient solar energy harvesting and conversion.