All‐Solution‐Processed HgTe Quantum Dot Photodetectors for Extended Short‐Wavelength Infrared Range Enhanced by Plasmonic ITO Nanocrystals

ABSTRACT Enhancing the absorption of the photodetector's active layer within the target spectral range is a key strategy for improving the device performance. Strong near‐field light localization in carefully engineered metal or oxide metasurfaces coupled to semiconductor quantum dots (QDs) enables efficient and wavelength‐selective photodetection, but such structures are typically complex and require expensive fabrication. Here, we introduce an up‐scalable, all‐solution process to realize photodetectors operating in the extended short‐wavelength infrared (ESWIR) range, using colloidal plasmonic In 2 O 3 :Sn,F (commonly abbreviated as ITO) nanocrystals (NCs) coupled to colloidal HgTe QDs, which boosts the optical absorption of HgTe QDs across the range from 1500 to 3000 nm. The responsivity of photodetectors to blackbody illumination reaches over 40 A/W within the 180–240 K temperature range, and the photocurrent spectrum is tailored thanks to the localized surface plasmon resonance of the ITO NCs. An In 2 O 3 shell further grown around ITO NCs allows us to suppress the dark current, albeit at the cost of the exciton‐plasmon coupling strength. The specific detectivity remains in the range from 10 11 to 10 10 Jones as the operating temperature is varied from 160 to 260 K, establishing a pathway for all‐colloidal materials‐based ESWIR photodetectors compatible with cryogen‐free cooling systems.