Colloidal Quantum-Dot Infrared Detectors and Focal Plane Arrays

Colloidal quantum dot (CQDs), a class of semiconductor nanocrystals synthesized via solution-phase methods, exhibit immense application potential in the field of infrared detection owing to their inherent advantages such as precise bandgap engineering enabled by quantum confinement effect, low manufacturing costs benefitted from complementary metal oxide semiconductor (CMOS)-compatible integration processes, and exceptional flexibility in device architectures without the limitation from lattice mismatch. This chapter systematically summarizes the research progress on colloidal quantum dot-based infrared photodetectors, with a particular focus on the synthesis and properties of colloidal quantum dots, single-element CQDs based photodetectors, CQDs focal plane arrays (CQDs FPAs), and CQDs based upconverters. First, the synthesis methods (organic-phase, aqueous-phase, hot-injection, cation exchange) and performance characteristics (bandgap width, crystal stability, carrier mobility) of typical CQD systems (CdTe, InAs, PbS, Ag₂X (X = Se, Te), HgTe) are elaborated, with emphasis on how bandgap engineering and solution processing underpin their spectral adaptability and manufacturing scalability. Then, the operating mechanisms, structural designs (vertical/planar architectures), and optimization strategies (ligand/interface engineering, doping) of single-element photoconductive, photovoltaic, and phototransistor CQD photodetectors are discussed. For CQDs FPAs, this chapter covers recent progress in near infrared, short-wave infrared, mid-wave infrared, and broadband imaging, highlighting how solution processing enables large-scale arrays with small pixel pitches and monolithic CMOS integration. As an emerging infrared visualization technique, the mechanism and operating principle of infrared-to-visible converters are discussed and summarized. This chapter also analyzes current challenges and outlines future directions, providing systematic references for advancing infrared CQDs photodetector technology toward practical, high-performance applications.