Surface-Neutralized HgCdSe Quantum Dots for High-Detectivity Infrared Photodetectors.

Authors

Wonseok Lee, Su Hwan Lee, Sang Hyun Nam, Min-Jae Si, Se-Woong Baek, Young-Hoon Kim, Andrew M Smith

Published in

Nano letters. Jul 07, 2026. Epub Jul 07, 2026.

Abstract

Infrared (IR) photodetectors used in advanced imaging and sensing applications rely on epitaxially grown semiconductors that are expensive to manufacture. Colloidal quantum dots (QDs) offer lower-cost production, with substantial progress using PbS and HgTe QDs. HgSe and HgCdSe QDs offer wide spectral tunability, higher absorption coefficients, and air stability, but their inherent n-type doping has hindered their use. Here, we show that n-type doping can be depleted by neutralizing nanocrystal surfaces by displacing surface metal cations acting as Z-type ligands. Heating with alkanethiols yields QDs coated with protonated thiols and with unfilled conduction bands. Surface-neutralized HgSe and HgCdSe QDs exhibit sharp excitonic absorption features at IR wavelengths up to ∼1700 nm. Photodiodes fabricated from HgCdSe QDs have a room-temperature specific detectivity of 1.4 × 10¹² Jones at 1355 nm, attributable to suppressed doping and low dark current. These air-stable, broadly tunable materials with strong IR absorption may enable low-cost IR sensors.

PMID:
42412912
Bibliographic data and abstract were imported from PubMed on 08 Jul 2026.

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