A near-infrared Sn-Pb perovskite imager with monolithic integration

Solution-processed Sn-Pb perovskites have emerged as promising candidates for near-infrared (NIR) photodetectors due to their low-cost, tunable bandgap and scalable fabrication. However, Sn²⁺ oxidation creates Sn vacancies and undesirable p-type doping, resulting in high dark current and limited detectivity, which hinder the practical deployment of Sn-Pb perovskite photodetectors. Herein, we propose a Sn(SCN)₂ inorganic molecular surface passivation strategy to suppress Sn²⁺ oxidation, significantly reduce surface defect density and enhance the optoelectronic properties (a dark current density of 10 nA cm^-2 at a bias of -0.1 V and a high specific detectivity of ~1.6 × 10¹³ Jones). Leveraging this approach, we report the monolithically integrated Sn-Pb perovskite NIR imager with a complementary metal-oxide-semiconductor readout circuit. The imager, featuring a 640 × 512 pixel array with a 15 μm pixel pitch, achieves an external quantum efficiency of 76% at 940 nm and a modulation transfer function of 206.5 LW/PH at 50%. Furthermore, the Sn-Pb perovskite imager demonstrates advanced material recognition capabilities, including liquid identification, underscoring its potential in chemical sensing, biomedical imaging and industrial inspection.