Enhancing the optoelectronic properties of SnS via mixed-phase heterostructure engineering†

Abstract

SnS holds great promise in optoelectronics, especially in photovoltaic devices, due to its exceptional intrinsic electronic properties and optimal optical absorption. However, its prospective applications are often limited by structural instability or oxidation, leading to internal or external defect states. This study proposes a mixed-phase SnS/h-BN heterostructure to enhance chemical and thermal stability while preserving the intrinsic optoelectronic properties of SnS. High negative binding energy and ab initio molecular dynamics simulations confirm the structural and thermal stability of the heterostructure up to 600 K. The heterostructure exhibits a type-I band alignment with an indirect density functional theory (DFT) band gap of 1.38 eV, corrected to 2.20 eV using Green's function with screened Coulomb potential (GW) calculations. The vertical intralayer electric field, resulting from non-uniformity in charge dynamics within the heterostructure, influences the SnS bound excitons, causing reduction in their binding energies. The weakly bound excitons indicate effective charge separation, charge transport augmentation, and a prolonged recombination lifetime. The interface effectively combines the excellent light-harvesting capabilities of SnS with the remarkable stability of h-BN, retaining the desirable optoelectronic properties of SnS while offering enhanced charge transport and stability.