Synergistic Piezophototronic and Bandgap Engineering in a Flexible MoTe2/In2Se3 Heterojunction Photodetector

Abstract

Two-dimensional materials provide a versatile platform for flexible optoelectronics. However, previous strain-engineered flexible photodetectors have generally exhibited a narrow spectral range, with most studies focusing solely on the visible range and lacking broadband response capability. Here, we present a flexible photodetector based on the MoTe₂/In₂Se₃ van der Waals heterojunction, where the piezophototronic effect and strain-induced bandgap modulation are combined to achieve a strain-enhanced broadband response from the visible to the short-wave infrared. Under controlled uniaxial tensile strain, the induced piezo-potential within the heterojunction significantly enhances the built-in electric field at the interface, while the strain-reduced bandgap of MoTe₂ synergistically promotes photocarrier generation and separation. Consequently, the device exhibits a broadband photoresponse and pronounced responsivity enhancements of 191% at 638 nm and 260% at 1310 nm under optimized tensile strain, along with an ultralow dark current of 9.4 pA. These results demonstrate an effective strain-modulated photon-to-electron transition in flexible van der Waals heterostructures and offer a viable strategy for designing high-performance flexible optoelectronic devices.