Synergism in Binary Nanocrystals Enables Top-Illuminated HgTe Colloidal Quantum Dot Short-Wave Infrared Imager

Thanks to their tunable infrared absorption, solution processability, and low fabrication costs, HgTe colloidal quantum dots (CQDs) are promising for optoelectronic devices. Despite advancements in device design, their potential for imaging applications remains underexplored. For integration with Si-based readout integrated circuits (ROICs), top illumination is necessary for simultaneous light absorption and signal acquisition. However, most high-performing traditional HgTe CQD photodiodes are p-on-n stack and bottom-illuminated. Herein, we report top-illuminated inverted n-on-p HgTe CQD photodiodes using a robust p-type CQD layer and a thermally evaporated Bi₂S₃ electron transport layer. The p-type CQD solid is achieved by exploring the synergism in binary HgTe and Ag₂Te CQDs. These photodetectors show a room-temperature detectivity of 3.4 × 10¹¹ jones and an EQE of ∼44% at ∼1.7 μm wavelength, comparable to the p-on-n HgTe CQD photodiodes. A top-illuminated HgTe CQD short-wave infrared imager (640 × 512 pixels) was fabricated, demonstrating successful infrared imaging.