A Lead Selenide Thin Film Heterojunction Photodetector with In-situ Sensitized Strategy

Owing to its suitable bandgap, low Auger recombination coefficient, and mature fabrication processes, lead selenide (PbSe) has emerged as a promising material for mid-wavelength infrared (MWIR, $3-5 \mu \mathrm{m}$) photodetection. Developing high-performance uncooled mid-wavelength infrared detectors is a challenging task. In this study, we prepared a PbSe photosensitive film using an in-situ sensitization strategy via chemical bath deposition (CBD), and subsequently designed and fabricated an uncooled polycrystalline PbSe/PbS colloidal quantum dots (CQDs) heterojunction photovoltaic(PV) detector. The device exhibited a dark current of $2.05 \times 10^{-5} \mathrm{~A} / \mathrm{cm}^{2}$ at -0.1 V, achieved an external quantum efficiency (EQE) of 6.65% at 0 V under 1650 nm LED illumination, and demonstrated a response time of $27.05 \mu \mathrm{~s}$ at 0 V, significantly outperforming photoconductive (PC) devices fabricated from this film. Furthermore, the fabrication process of these PbSe/PbS quantum dots PV detectors enable high reproducibility and yield, making them promising candidates for low-cost, high-performance, uncooled focal plane array imaging in commercial applications.