High-Performance Wide-Spectrum Si:PbS CQD Photodetector with Passivated Interface States

Lead sulfide (PbS) colloidal quantum dots (CQDs) are widely used due to their tunable bandgap and high compatibility in composite integration with silicon, expanding the spectral response range of silicon-based photodetectors from visible light to short-wave infrared. The silicon dangling bonds were effectively passivated through CH3I, and the band alignment at the heterojunction interface was adjusted. It reduces electron recombination at the interface, thereby achieving a broad spectral response of silicon-based PbS CQDs heterojunction photodetectors spanning from 380 nm to 1600 nm. As per the research findings, Si:PbS CQDs photodetectors passivated with CH₃I showcase impressive characteristics with a rectification ratio of 1.2× 10² and a high on-off ratio of 3.1× 10³. These characteristics underscore a remarkable photovoltaic effect within the detectors. The detector achieves an average external quantum efficiency of 37% in the visible and short wave infrared spectrum. At 1470 nm, the responsivity of the Si:PbS CQDs photodetector reaches 0.22 A/W, with a detectivity of 3.3×10¹¹ Jones, marking a 28-fold increase compared to the Si:PbS CQDs photodetector without CH₃I passivation. This work offers a new strategy for manufacturing low-cost, high-performance PbS CQDs photodetectors compatible with silicon arrays.