Interface designed MoS2/GaAs heterostructure solar cell with sandwich stacked hexagonal boron nitride

Abstract

MoS₂ is a layered two-dimensional semiconductor with a direct band gap of 1.8 eV. The MoS₂/bulk semiconductor system offers a new platform for solar cell device design. Different from the conventional bulk p-n junctions, in the MoS₂/bulk semiconductor heterostructure, static charge transfer shifts the Fermi level of MoS₂ toward that of bulk semiconductor, lowering the barrier height of the formed junction. Herein, we introduce hexagonal boron nitride (h-BN) into MoS₂/GaAs heterostructure to suppress the static charge transfer and the obtained MoS₂/h-BN/GaAs solar cell exhibits an improved power conversion efficiency of 5.42%. More importantly, the sandwiched h-BN makes the Fermi level tuning of MoS₂ more effective. By employing chemical doping and electrical gating into the solar cell device, PCE of 9.03% is achieved, which is the highest among all the reported monolayer transition metal dichalcogenide based solar cells.