Mixed quantum dot film for dual-band infrared detection

•We prepare photoconductive films composed of PbS quantum dots with multiple excitonic peaks.•Mixed quantum dots films shows adjustable absorbance.•Mixed quantum dots films were successfully used to fabricate dual-band photodetectors.•Photoconductors based on mixed quantum dots film have a significantly higher responsivity. Dual-band infrared detection offers enhanced spectral information crucial for improved target identification. Traditional dual-band infrared photodetectors have often relied on expensive epitaxial growth bulk materials, limiting their widespread use in civilian applications. Colloidal quantum dots present an affordable alternative for dual-band infrared detection, owing to their spectral tunability and solution processability. In this study, we have developed an approach utilizing mixed lead sulfide quantum dot films to achieve dual-band infrared detection spanning the NIR (Near Infrared) and SWIR (Short Wave Infrared) ranges. These films exhibit a broad absorption spectrum, ranging from 400 to 1600 nm. When operating within the near-infrared band, the device based on mixed quantum dot films demonstrates an responsivity of 0.18A/W and specific detectivity of 2.38 × 109cm∙Hz1/2/W near 900 nm.While operated in the SWIR band, the detector has responsivity of 0.17A/W and specific detectivity of 2.11 × 109cm∙Hz1/2/W near 1600 nm.