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

Identifying two-dimensional (2D) high-efficiency solar photovoltaic devices remains an urgent challenge in addressing current energy demands. Considering the limits of isolated 2D systems in photovoltaics, one most effective solution is stacking them into van der Waals heterostructures (vdWHs). However, the favorable factors for photovoltaics in vdWHs is still uncertain, nor the intrinsic principles is clear. Here, based on monolayer InSe and β-Sb, we propose a boosting strategy on photovoltaics through stacking them into vdWH. After confirming its experimental feasibility, several superior photovoltaic characteristics of such vdWH are verified than its components. Including more moderately indirect-to-direct band gap, higher electron mobilities, the hindrance of carrier recombination due to the staggered type-II band alignment, and the stronger and red-shifted optical harvesting abilities owing to the band redistribution. In addition, superior characteristics in the InSe/Sb vdWH based photovoltaic devices are further confirmed, including 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 (Rph ,τeqe et.al.) than each component and many other typical vdWHs. Obviously, the design principles and promotion mechanisms of 2D vdWH on photovoltaics can provide powerful theoretical guidances for next design and applications of 2D high-efficiency solar photovoltaic cells.