Strain engineered electro-optic and opto-electronic conversion in InSe Schottky junctions

Layered indium selenide (InSe) emerges as a promising candidate for next-generation optoelectronics, yet achieving dynamically reconfigurable near-infrared light sources and photodetectors in these devices remains challenging. Here, we demonstrate a strain-engineered bifunctional device based on a vertical graphene/γ-InSe/graphene Schottky junction on a flexible polypropylene (PP) substrate. By exploiting the large thermal expansion coefficient (CTE) mismatch between InSe and PP, reversible biaxial strain is precisely induced in situ via thermal control. Under electro-optic operation, compressive strain widens InSe's bandgap via lattice distortion, generating a pronounced blueshift (up to 65 meV) in the electroluminescence (EL) peak. For opto-electronic conversion, strain-mediated modulation of Schottky barrier height suppresses dark current while modulating photocurrent and photoresponsivity under 532 nm and 980 nm illumination. This work establishes strain as a new strategy for reconfigurable InSe-based optoelectronic devices.