Passivating {100} Facets of PbS Colloidal Quantum Dots via Perovskite Bridges for Sensitive and Stable Infrared Photodiodes

Abstract Solution‐processed PbS colloidal quantum dots (CQDs) are promising optoelectronic materials for next‐generation infrared imagers due to their monolithic integratability with silicon readout circuit and tunable bandgap controlled by CQDs size. However, large‐size PbS CQDs (diameter >4 nm) for longer shortwave‐infrared photodetection consist mainly of {100} facets with incomplete surface passivation and unsatisfied stability. Here, it is reported that perovskite‐bridged PbS CQDs, in which the {100} facets of the CQDs are epitaxially bridged with CsPbI 3– x Br x perovskite, can achieve improved passivation and enhanced stability in comparison with the traditional strategies. The resultant infrared CQDs photodiodes exhibit significantly reduced dark current, nearly 50% enhanced photoresponse, and improved work stability. These superior properties synergistically produce the most balanced performance (with a high −3 dB bandwidth of 42 kHz and an impressive specific detectivity of 6.2 × 10 12 Jones) among the reported CQDs photodetectors.