First-principles prediction of optoelectronic properties in two-dimensional Cs₂PbI₂Cl₂/WS₂ van der Waals heterojunction

Designing two-dimensional (2D) semiconductor van der Waals (vdW) heterojunctions is an effective strategy for realizing multifunctional microelectronic devices. In this work, we present the detailed calculations to investigate the optoelectronic properties of the vdW C s 2 Pb I 2 C l 2 / W S 2 heterojunction composed of 2D perovskite C s 2 Pb I 2 C l 2 and tungsten disulfide W S 2 by using the density functional theory. The calculated electronic structures show that the 2D C s 2 Pb I 2 C l 2 / W S 2 heterojunction exhibits a type-II band alignment with a band gap of 2.08 eV and high optical absorption coefficients in the visible light and ultraviolet light ranges, with a peak reaching 4 . 1 × 1 0 5 c m − 1 at 4.1361 eV (299.78 nm). The calculated charge carrier mobilities of 2D C s 2 Pb I 2 C l 2 / W S 2 heterojunction were dominated by electrons, with the maximum mobility rate reaching 7741.11 c m 2 · V − 1 · s − 1 . Combining the Shockley-Queisser limit with first-principle calculations, the predicted power conversion efficiencies of 2D C s 2 Pb I 2 C l 2 / W S 2 heterojunction were compared and discussed by employing different functionals . The above research provides a theoretical basis for the design of efficient 2D vdW photonic devices in future.