A research team in Spain has developed a low-cost colloidal quantum dot photodetector capable of sensing in the long-wave infrared (IR), with the potential to replace currently available, more expensive commercial solutions (Nano Lett., doi: 10.1021/acs.nanolett.9b04130). The new technology fills an existing gap in the photodetection spectrum and, according to the researchers, may prove useful for applications like environmental monitoring, food inspection, and gas analysis.
Up to this point, photodetector technology has been rather fragmented, with silicon photodetectors readily available for the visible/near-IR range and InGaAs photodetectors for the short-wave IR region. While devices do exist for the mid- and long-wave IR—for example, CdHgTe or more exotic detectors—they tend to be costly, complex to manufacture, and not CMOS-compatible.
To get to a less costly alternative, Gerasimos Konstantatos of ICFO–The Institute of Photonic Sciences and his colleagues thought about creating a mid- and long-wave IR photodetector with colloidal quantum dots (QDs). In particular, they decided to focus on lead chalcogenide (PbS) colloidal QDs, since earlier studies with the material in solution reported steady-state intraband absorption within the conduction band.