A Boosting Strategy of Photovoltaics by Stacking Monolayer InSe and β-Sb into Heterostructure

Identifying two-dimensional (2D) solar photovoltaic devices with high efficiency remains an urgent challenge in addressing current energy demands. Considering the limitations of isolated 2D systems in the photovoltaic applications, the most effective solution is stacking them into van der Waals heterostructures (vdWHs). However, the favorable factors for photovoltaics in vdWHs are still uncertain, nor is their intrinsic enrichment or enhancement mechanism on photovoltaics being clear. Here, based on the typical monolayer transition metal-chalcogenide compound InSe and β-phase antimonene (Sb), we propose a boosting strategy on photovoltaic performances by stacking them into the InSe/Sb vdWH. After confirming the feasibility of its experimental synthesis, several superior photovoltaic related characteristics are verified than its components. Including the more moderately sized indirect to direct band gap, the higher electron mobilities than those of monolayer InSe, the hindrance of carrier recombination due to the staggered type-II band alignment, and the stronger and red-shifted optical harvesting abilities because of the band redistribution. In addition, further researches are conducted on the additional superior characteristics of such stacked InSe/Sb vdWH in 2D photovoltaic devices. Such as the red-shifted photocurrent into the infrared light range, the superior photoelectric conversion efficiencies in the visible light region, and the higher photovoltaic quality factors including the photon responsivity $$ and external quantum efficiency $$ than its components and many other typical vdWHs. Therefore, we have not only proposed a InSe/Sb vdWH with superior performances and potential applications in photovoltaics, but the formation principles of the type-II band alignment in the vdWH accompany with its promotion mechanisms on solar photovoltaics can provide powerful theoretical guidances for future experimental design and preparation of 2D high-efficiency photovoltaic devices.