Unveiling the synergistic impact of asymmetric oxygen doping and biaxial strain on the photoelectric properties of GaSe/MoS2 heterojunctions: A first-principles study

Abstract

A systematic investigation was conducted into the electronic structure and optical property regulation mechanisms of GaSe/MoS₂ heterojunctions. The investigation was based on first-principles calculations. The built-in electric field induced by interfacial electron migration was significantly enhanced under combined O doping and strain regulation. This enhancement has been demonstrated to result in improved charge separation efficiency. Applying biaxial tensile strain to the doped system has resulted in a transition from an indirect bandgap to a direct bandgap. The bandgap value has gradually decreased from 0.98 eV (eV) at 2 % strain to 0.59 eV at 8 % strain.Conversely, compressive strain initially reduces the bandgap value of the doped system and subsequently causes it to increase gradually, reaching a maximum of 1.55 eV. Furthermore, optical analysis demonstrates that O doping exerts a suppressive effect on enhancing optical peak intensity through precisely calibrating electronic states. Strain instigates red shifts in absorption and reflection peaks, modulating the energy level distribution and expanding the photoresponse range. This study unveils a practical approach to regulating the optical properties of two-dimensional heterojunctions through the synergistic effects of doping and strain, thus providing significant references for designing efficient optoelectronic devices. Furthermore, it provides a theoretical basis for applying GaSe/MoS₂ heterojunctions in optoelectronic devices.