Quantum Dot Photodetector Technology

Colloidal quantum dots (QDs) are already establishing their place in mass market as their significance in enabling bright displays with true colors has become obvious. In parallel, decades of exploration of QDs’ superb light absorption properties are resulting in very impactful demonstrations of photodetectors and image sensors. Thanks to the possibility to deposit them from solution by means of coating, monolithic integration with underlying readout circuitry becomes facile. One implementation category is on flat-panel-display backplanes with thin-film transistors that can lead to large-area, flexible, transparent, free-form-factor scanners. Another one is on wafers with complementary metal-oxide-semiconductor transistors that result in high-resolution, high-pixel density image sensors with spectral sensitivity inaccessible for silicon-based counterparts, such as in short-wave infrared (SWIR) and mid-wave infrared (MWIR; beyond the cut-off wavelength of Si). In this chapter, we introduce the implementations and applications of QD devices for photodetection. We start by explaining different device architectures used for light absorption. Then, we review figures of merit relevant at different stages of development (material, stack, photodetector, and image sensor). We go into the particularities of material and stack design when optimized for light sensitivity and present the recent advances for different QD absorber types (focusing on PbS, InAs, InSb, HgTe, AgTe, and AgSe). Finally, we describe different use cases and give a market outlook for light sensors based on QDs.