Strain-Decoupled Flexible InAs CQD SWIR Imager for Through-Silicon Photovoltaic Inspection

Abstract

Artificial vision systems for photovoltaic (PV) inspection require lightweight, mechanically compliant infrared imagers capable of resolving buried defects nondestructively. Yet short-wave infrared (SWIR) technologies remain dominated by rigid epitaxial semiconductors, while flexible thin-film alternatives are limited by the fragility of the photoactive layer. Here we report a flexible SWIR imager based on InAs/ZnSe colloidal quantum dots (CQDs) for through-silicon PV inspection, enabled by a strain-decoupled architecture. Soft lift-off lithography patterns the CQD active layer into an island–bridge layout that relieves mechanically induced stress. The imager exhibits micrometer-scale pattern fidelity, good pixel uniformity, an average dark current of 10^–6 mA per pixel, and an average external quantum efficiency (EQE) of ∼14%. It maintains stable operation under repeated bending and twisting, with only ∼6% modulation transfer function (MTF) degradation after severe mechanical deformation. Under eye-safe 1550 nm illumination, the device enables through-silicon imaging with a signal-to-noise ratio (SNR) of ∼9 and resolves distinct PV cell components with clear contrast. These results establish flexible heavy-metal-free CQD imagers as a viable route toward compact artificial vision platforms for through-silicon, nondestructive PV diagnostics.