Colloidal Quantum Dots-Based Three-Band Infrared Photodetector with the Bias-Tunable Spectral Response

Multiband infrared photodetectors (PDs) have garnered considerable attention due to their potential in various fields such as biomedical applications, optical communications, and military operations. However, the lattice mismatch of mature bulk semiconductors with varying bandgaps in the same PD pixel has impeded the advancement of multiband infrared detectors. Colloidal quantum dots (CQDs), with adjustable bandgaps, wide spectral range, and easy solution processing are promising materials for the fabrication of multiband infrared detectors. Herein, HgTe CQDs are used with varying bandgaps to construct a three-band infrared detector with short-wave infrared of 1.7 and 2.4 μm and midwave infrared of 4 μm. The utilization of Ag₂Te nanocrystals to bring in spatially stable doping is the key to achieving three-band infrared detectors. Through adjusting bias polarity, the detectors switch between a three-band mode and a dual-band mode. The detector exhibits exceptional detection performance, with detectivity above 3 × 10¹⁰ Jones in three-band mode.