Ultra-low dark current self-powered 0.36–1.7 μm broadband photodetector with tungsten oxide as interface modification layer

Lead sulfide colloidal quantum dots (PbS CQDs) exhibit tunable infrared bandgaps via quantum confinement but suffer from trap states predominantly localized on {100} facets, which severely degrade device performance in large CQDs due to increased facet exposure. To address the persistent challenge of fabricating high-quality large CQD films (>1.7 μm exciton peak), we developed a solution-phase exchange method to synthesize defect-controlled PbS CQDs. Furthermore, a self-powered p-i-n photodetector integrating a WOx interfacial modification layer was engineered. The WOx layer enhances contact quality at the metal electrode/PbS CQD film interface, which achieves an ultra-low dark current density of 4.54 nA cm −2 at −0.5V. Then, the device demonstrates excellent responsivity and detectivity across a broad range of illumination wavelengths, from 0.36 μm to 1.7 μm. Notably, the device achieves an exceptional detectivity for infrared light at 1.7 μm, exceeding 10 10 Jones. These findings pave the way for designing and developing novel device structures for high-performance infrared photovoltaic detectors with extended wavelength capabilities.