Tailoring the Energy Funneling across the Interface in InSe/MoS2 Heterostructures by Electrostatic Gating and Strain Engineering

Abstract

AbstractAs a representative 2D semiconductor in the III–VI family, indium selenide (InSe) retains both high carrier mobility and direct bandgap even down to few‐layer limit. However, it exhibits relatively weak light absorption of normally incident light due to its unique optical anisotropy different from transition metal dichalcogenides, significantly impeding its optoelectronic applications. Herein, it is demonstrated that the light emission of InSe can be enhanced by a maximum of 2.5 times via energy funneling effect in MoS2/InSe type‐I heterostructures, the band alignment and charge transfer process of which are explored by optical spectroscopic technique, Kelvin probe force microscopy, and optoelectronic measurements. The energy funneling effect in MoS2/InSe heterostructure is not only significantly tuned by electrostatic gating, but also preserves high efficiency upon applying a uniaxial tensile strain up to 0.52%, making it appropriate for both rigid and flexible superior optoelectronic devices. Besides, the charge transfer at the heterointerface in MoS2/InSe changes from funneling to exciton dissociation via layer engineering of MoS2, with a maximum hole transfer rate of 9 × 108 s−1 from InSe to MoS2. This work provides approaches to tune the charge transfer across the van der Waals heterointerface, giving rise to promising applications in quantum optoelectronics.