High-Power Genuine Ultraviolet Light-Emitting Diodes Based On Colloidal Nanocrystal Quantum Dots

Thin-film ultraviolet (UV) light-emitting diodes (LEDs) with emission wavelengths below 400 nm are emerging as promising light sources for various purposes, from our daily lives to industrial applications. However, current thin-film UV-emitting devices radiate not only UV light but also visible ligh...

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Bibliographic Details
Published in:Nano letters 2015-06, Vol.15 (6), p.3793-3799
Main Authors: Kwak, Jeonghun, Lim, Jaehoon, Park, Myeongjin, Lee, Seonghoon, Char, Kookheon, Lee, Changhee
Format: Article
Language:English
Subjects:
Cadmium Compounds - chemistry
Colloids
Nanoparticles - chemistry
Quantum Dots - chemistry
Sulfides - chemistry
Ultraviolet Rays
Zinc Compounds - chemistry
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Summary:Thin-film ultraviolet (UV) light-emitting diodes (LEDs) with emission wavelengths below 400 nm are emerging as promising light sources for various purposes, from our daily lives to industrial applications. However, current thin-film UV-emitting devices radiate not only UV light but also visible light. Here, we introduce genuine UV-emitting colloidal nanocrystal quantum dot (NQD) LEDs (QLEDs) using precisely controlled NQDs consisting of a 2.5-nm-sized CdZnS ternary core and a ZnS shell. The effective core size is further reduced during the shell growth via the atomic diffusion of interior Cd atoms to the exterior ZnS shell, compensating for the photoluminescence red shift. This design enables us to develop CdZnS@ZnS UV QLEDs with pure UV emission and minimal parasitic peaks. The irradiance is as high as 2.0–13.9 mW cm–2 at the peak wavelengths of 377–390 nm, several orders of magnitude higher than that of other thin-film UV LEDs.
ISSN:1530-6984
1530-6992
DOI:10.1021/acs.nanolett.5b00392