High-Performance and Stable HgTe Colloidal Quantum Dot Photodiodes Enabled by Hybrid Passivation

HgTe colloidal quantum dots (CQDs) hold great promise for the next generation of low-cost and large-format infrared imagers. The implementation of the ZnO/HgTe/ZnTe double heterojunction enables HgTe imagers in photovoltaic mode. However, it remains challenging to further improve the performance and stability of the detector. Here, we propose a hybrid passivation strategy employing methylammonium iodide (MAI) and HgI₂ to address this challenge. This approach generates strongly bound X-type HgI₃^- ligands that effectively passivate the HgTe CQDs surface. The hybrid passivated HgTe CQDs demonstrate enhanced colloidal stability and surface passivation, which translate into improved detector performance and stability. The resulting photodetector achieves a remarkable external quantum efficiency (EQE) of 66.8% at 1620 nm under zero bias, a specific detectivity of 1.45 × 10¹² Jones, and a dark current density as low as 185 nA/cm². The HgTe CQD detectors were successfully integrated with thin-film transistor (TFT) readout circuits. The enhanced stability of the detectors based on hybrid passivated HgTe CQDs was verified at both the single-pixel and array levels.