Mid-Infrared Intraband Photodetector via High Carrier Mobility HgSe Colloidal Quantum Dots

In this work, a room-temperature mixed-phase ligand exchange method is developed to obtain a relatively high carrier mobility (similar to 1 cm(2)/(V s)) on HgSe intraband colloidal quantum dot solids without any observable trap state. What is more, the doping from 1S(e) to 1P(e) state in the conduction band could be precisely controlled by additional salts during this method, proved by optical and transport experiments. The high mobility and controllable doping benefit the mid-infrared photodetector utilizing the 1S(e) to 1P(e) transition, with a 1000fold improvement in response speed, which is several mu s, a 55fold increase in responsivity, which is 77 mA/W, and a 10-fold increase in specific detectivity, which is above 1.7 x 10(9) Jones at 80 K. The high-performance photodetector could serve as an intraband infrared camera for thermal imaging, as well as a CO(2 )gas sensor with a range from 0.25 to 2000 ppm.