Unveiling the photoelectric and photocatalytic promise of two-dimensional lead-free perovskite/InX (X=Se, Te) van der Waals heterostructures

Two-dimensional (2D) perovskites and InX (X=Se, Te) monolayers have garnered global attention due to their extraordinary performance as environment-friendly and low-cost candidates for photoelectric and photocatalytic applications. Herein, we provided a comprehensive understanding on the crystal structures, stabilities, electronic and optical properties of lead-free Cs₃Bi₂I₉/InX (X=Se, Te) van der Waals (vdW) heterostructures as well as their potential applications in photoelectric conversion and photocatalysis based on density functional theory calculations. It is highlighted that Cs₃Bi₂I₉/InX heterostructures exhibit significantly reduced bandgaps and enhanced light absorption capacity, along with noticeable improvements in carrier mobilities compared to their corresponding monolayers. By combining the type-II band edge natures with appropriate bandgap vales, Cs₃Bi₂I₉/InX heterostructures hold tremendous potential in the fields of photoelectric conversion and photocatalysis applications. It is worth emphasizing that the maximum photoelectric conversion efficiencies of Cs₃Bi₂I₉/InSe and Cs₃Bi₂I₉/InTe heterostructure film solar cells are 24.11 % and 26.23 %, respectively. The present results will provide fundamental understanding and good theoretical guidance for rationally constructing vdW heterostructures based on 2D perovskites in the field of photo energy conversion.