Photocatalytic water splitting is a promising method which uses the sunlight to directly generate hydrogen from water in meeting the requirement of energy consumption. Inspired by the experimental realization of...

The bandgaps for monolayers Bi2Se3, Bi2Se2Te and Bi2SeTe2 decrease under moderate strains ranging from −4% to 10%, and the predicted electron mobilities are high, reaching 2708 cm2 V−1 s−1 for Bi2SeTe2.

Recently, excitonic solar cells (XSCs) with high photovoltaic performance have raised research interests because of their high power conversion efficiencies (PCEs). Herein, by using first-principles calculations, we predict that γ-BX (X = S, Se, Te) monolayers are direct semiconductors with the band gaps of 2.94, 2.71, and 1.32 eV, respectively, and maintain semiconduction in the broad strain range of 0% ≤ δ ≤ 5%. The moderate direct band gap, high transport property, dramatically high absorption from visible to the ultraviolet region, and extraordinary excitonic behavior of monolayer γ-BTe, render it promising for next-generation optoelectronic and photovoltaic devices. By choosing monolayer GeP 2 as a proper acceptor material, the practical upper limit of PCE for the heterobilayers of γ-BTe/GeP 2 reaches up to 21.76% (22.95% under strain), comparable to typical heterobilayer solar cells, making it a competitive donor material for photovoltaic device applications.