Non‐Toxic CuInS2/ZnS Colloidal Quantum Dots for Near‐Infrared Light‐Emitting Diodes

Ternary CuInS2 quantum dots (QDs) with photoluminescence that is tunable from the visible to the near‐infrared (NIR) region are promising light‐emitters for consumer electronics due to the absence of toxic elements such as Pb, Cd, or As. Despite the compelling performance of visible‐light‐emitting C...

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Bibliographic Details
Published in:Advanced materials (Weinheim) 2023-07, Vol.35 (28), p.e2301887-n/a
Main Authors: Lim, Li Jun, Zhao, Xiaofei, Tan, Zhi‐Kuang
Format: Article
Language:English
Subjects:
CuInS2
Efficiency
Emissions control
Emitters
Lead
Light emitting diodes
Materials science
Near infrared radiation
NIR emission
non‐toxic materials
Nucleation
Perovskites
Photoluminescence
Quantum dots
Quantum efficiency
Synthesis
Zinc sulfide
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Summary:Ternary CuInS2 quantum dots (QDs) with photoluminescence that is tunable from the visible to the near‐infrared (NIR) region are promising light‐emitters for consumer electronics due to the absence of toxic elements such as Pb, Cd, or As. Despite the compelling performance of visible‐light‐emitting CuInS2 QDs, reports on NIR emission remain limited, with modest efficiencies at wavelengths beyond 900 nm. In this work, the facile synthesis of NIR‐emitting CuInS2/ZnS QDs is reported. A combination of two sulfur precursors w as used in the synthesis, comprising 1‐dodecanethiol (DDT) and hexamethyldisilathiane (HMDS). The reactive HMDS facilitates faster nucleation and leads to a higher density of emissive Cu‐deficiency sites. The resulting QDs exhibit high photoluminescence quantum efficiency (PLQE) of 65% at a long emission wavelength of 920 nm. Using these QDs, NIR light‐emitting diodes (LED) are fabricated, which attain an external quantum efficiency (EQE) of 8.2%. This efficiency is comparable to the best reported PbS and InAs QD LEDs, and the emission wavelength exceeds that of lead iodide perovskites. This work thus marks one of the first reports of efficient NIR LEDs based on environmentally benign CuInS2 QDs and may open up promising new applications in consumer electronic products. The synthesis of CuInS2/ZnS quantum dots (QDs) with a high photoluminescence quantum efficiency (PLQE) of 65% at 920 nm is reported. Notably, the synthesis employs a supplementary S precursor, hexamethyldisilathiane (HMDS), which gives rise to better size homogeneity and an improvement in PLQE. Implementation of the QDs in a light‐emitting device gives an external quantum efficiency (EQE) of 8.2%.
ISSN:0935-9648
1521-4095
DOI:10.1002/adma.202301887