Dual‐Mode Flexoelectric Nanogenerators Activated by Light and Heat for Broad‐Spectral Photodetection and Thermal Response

ABSTRACT The flexoelectric effect, a polarization phenomenon unrestricted by material symmetry, holds great promise for next‐generation energy harvesting and sensing. However, conventional flexoelectric devices require external mechanical stress, which severely limits their practical applicability. Here, we present a heterojunction‐based dual‐mode flexoelectric nanogenerator that is driven by light and heat, requiring no external mechanical or electrical input. Under illumination (photodetection mode) or temperature variation (thermal response mode), the heterojunction components undergo differential deformation, generating a pronounced interfacial strain gradient that drives strong flexoelectric polarization and flexo‐photovoltaic currents. The photodetection mode demonstrates a broad spectral response from 250 to 600 nm, with a peak responsivity of 2.2 mA W −1 . The thermal response mode exhibits an effective pyroelectric coefficient as high as 7518 µC m −2 K −1 , surpassing conventional pyroelectric materials by over an order of magnitude. By eliminating the need for external stress, this work enables direct coupling among optical, thermal, mechanical, and electrical energies, opening a new avenue for self‐powered photodetectors and thermal sensors based on flexoelectricity.