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

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 CsPbI3-xBrx 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 x 10(12) Jones) among the reported CQDs photodetectors.