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CdHgSe/HgS/CdZnS colloidal quantum dots: Bright short-wave infrared nanoemitter

CdHgSe/HgS/CdZnS colloidal quantum dots: Bright short-wave infrared nanoemitter
Lee, GyudongJeong, WoohyeonSeo, JongcheolChung, Dae SungChoi, HyosungLyu, Hong-KunLim, Sung Jun
DGIST Authors
Chung, Dae Sung; Lyu, Hong-KunLim, Sung Jun
Issue Date
2019 Fall ACS National Meeting & Expo in San Diego
Bright short-wave infrared or second near-infrared (SWIR or NIR-II; wavelength = 1000–1700 nm) light emitters provide unique opportunities for deep tissue biological imaging, telecommunications, and night-time surveillance. Researchers have introduced various SWIR emitters including carbon nanotubes, molecular dyes, rare earth-doped nanoparticles, and semiconductor quantum dots. However, wavelength-tunable SWIR emitters with high quantum yield (QY) in the entire SWIR region has not been realized. In this work, we present the fabrication of a new bright SWIR light emitter by synthesizing CdHgSe/HgS/CdZnS colloidal quantum well (QW) structure. CdHgSe cores with NIR absorption (λabs ~750 nm) were prepared via Cd-to-Hg cation exchange on zinc-blende CdSe QDs. Then HgS emitting layer with controlled thickness (0.8-2.4 monolayers, MLs) was grown over the CdHgSe core to tune the emission wavelength in SWIR region. Finally, CdZnS protecting layer (typically CdZnS ~4ML) was overcoated to boost QY, increase photostability, and improve their resistance to surface modification necessary for water solubilization. Photoluminescence (PL) spectra showed that our SWIR QWs show narrow-band emission (FWHM <0.2 eV) which can be tuned in the entire SWIR region (1050-1550 nm). More importantly, absolute PL QYs of SWIR QWs can be maintained high at 50-90% in the most of SWIR region in 1000-1350 nm and reduced to 20-40% in 1350-1550 nm. Furthermore, SWIR QWs show bright emission in water (QY >40%) after applying with amphiphilic polymer coatings. In addition, we could fabricate high-intensity AC-driven LED devices with our SWIR QWs to produce electroluminescence covering the whole SWIR spectrum.
American Chemical Society
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Department of Energy Science and EngineeringPolymer Energy Materials Lab2. Conference Papers
Division of Electronics & Information System2. Conference Papers
Division of Nanotechnology2. Conference Papers

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