Reconfigurable Bulk Photovoltaics via Strain‐Gradient‐Induced Polar Reconstruction in a van der Waals Antiferroelectric

Strain gradients can induce flexoelectric polarization and activate bulk photovoltaic signals, but the response is usually locked to the localized flexoelectric polarization or intrinsic symmetry, limiting its reconfigurability. Van der Waals antiferroelectrics provide a distinct route: strain gradients can reconstruct inversion symmetry and polar evolution via interlayer sliding, converting a centrosymmetric parent crystal into a polar platform with a writable order parameter. Here, we demonstrate strain-gradient-induced interlayer sliding and polar reconstruction in flexural GeSe, and its direct transduction into reconfigurable bulk photovoltaic output. Correlative Raman/second-harmonic generation mapping and vector piezoresponse force microscopy reveal strain-gradient-induced symmetry breaking and an armchair-aligned polarization with asymmetric, direction-selective switching under lateral poling. Photocurrent mapping and polarization-resolved measurements identify a symmetry-allowed bulk photovoltaic current along the polar axis, whose magnitude is spatially programmable, increasing by over two orders of magnitude after polar reconstruction induced within the coupling of effective flexoelectric bias and ferroic order parameter. These results establish a general symmetry-on-demand strategy to program nonlinear photovoltaics in centrosymmetric van der Waals antiferroelectrics.