Quad-Band Short-Wave Infrared Detection Using Bandgap-Controlled Ag2Te Quantum Dots

Abstract

Multispectral photodetection in the short-wave infrared (SWIR) range has been highly desirable for applications such as night vision, quality inspection, and bio-imaging. Colloidal quantum dots (QDs) have been extensively explored as a promising alternative to conventional epitaxial semiconductors for multispectral photodetection owing to their size-tunable bandgap-controlled optoelectronic properties and potential for low-cost, high-throughput fabrication. Here, a multispectral SWIR photodetector is demonstrated based on four distinct sizes of heavy-metal-free Ag2Te QDs, each patterned side-by-side using a direct QD photopatterning process- involving QD film deposition, ultraviolet-induced selective QD ligand crosslinking, and pattern development. This enables precise spatial integration of the four different QD channels into a single device platform that is independently addressible, allowing integrated multispectral SWIR detection within a monolithic platform. The resulting multispectral Ag2Te QD channels show maximum responsivities of 188.4, 173.5, 155.6, and 185.8 mA W−1 at 1150, 1350, 1550, and 1800 nm, respectively. By leveraging the distinct photoresponses of four spectrally differentiated Ag2Te QD channels to SWIR input light, it is demonstrated that the multispectral photodetector enables simple, non-spectrometric wavelength identification—highlighting a unique capability unattainable with conventional single-size-QD devices.