First-principles investigations of structural, electronic and optical properties of janus GaXY (X/Y S, Se, Te)/GeAs van der Waals heterostructures for photovoltaic applications

In this study, the investigation of the structural, electronic and optical properties of Janus monolayers GaXY (X/Y S, Se, Te)/GeAs van der Waals (vdW) heterostructureshas been conducted via the use of Density Functional Theory (DFT). Two different models (I and II) have been employed, each including two stacking configurations (AA and AB). The direct band gaps observed in the GaSeTe/GeAs, GaSeS/GeAs, and GaSTe/GeAs, systems are measured to be 1.49, 1.77, and 1.41, respectively. Furthermore, the negative binding energies indicate that monolayers in both models exhibit a state of energy stability. Furthermore, all van der Waals (vdW) heterostructures demonstrate lower effective masses, a crucial factor ensuring high carrier mobilities. This characteristic is pivotal as it improves the efficiency of solar cells by facilitating enhanced charge transport. The optical properties of the GaXY (X/Y S, Se, Te)/GeAs van der Waals heterostructures were investigated, revealing a significant absorption coefficient in the visible region, indicating their strong capacity to absorb visible light. These findings indicate that the GaXY (X/Y S, Se, Te)/GeAs systems exhibit favorable properties that have potential for applications in optoelectronics and photovoltaics (PV).