Heterostructures can efficiently modulate the bandgap of semiconductors and enhance the separation of photocarriers, thereby enhancing the performance of optoelectronic devices. Herein, we design an InS/ZnIn2S4 van der Waals (vdW) heterostructure and investigate its electronic and photovoltaic properties using first principles calculation. Compared to its individual monolayers, the InS/ZnIn2S4 heterostructure not only possesses a smaller band gap of 2.21 eV and superior light absorption performance in the visible short-wavelength region (<500 nm) but also forms a type-II1 band alignment. Moreover, a large power conversion efficiency (PCE) of 10.86% is achieved. The transformation of the band alignment from type-II1 to type-I or type-II2 can be forced using an external electric field, and the PCE can be further increased up to 12.19% at a positive E ⊥ of 0.2 V Å-1. Within a critical biaxial strain of 4%, the type-II1 band alignment can be maintained, and a high PCE of 20.80% is achieved at a tensile strain (ε) of 4%. Our results may suggest a potential optoelectronic application direction for the InS/ZnIn2S4 heterostructure and offer effective means to enhance its optoelectronic device performance.
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