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Proceedings Paper

Development of solid state light sources based on II-VI semiconductor quantum dots
Author(s): Lauren E. Shea Rohwer; Billie L. Abrams; Jess P. Wilcoxon; Steven G. Thoma
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Paper Abstract

Solid state light sources based on integrating commercial near-UV LED chips with encapsulated CdS quantum dots are demonstrated. Blue, blue-green, and white quantum dot LEDs were fabricated with luminous efficiencies of 9.8, 16.6, and 3.5 lm/W, respectively. These are the highest efficiencies reported for quantum dot LEDs. Quantum dots have advantages over conventional micron-sized phosphors for solid state lighting, such as strong absorption of near-UV to blue wavelengths, smaller Stokes shift, and a range of emission colors based on their size and surface chemistry. Alkylthiol-stabilized CdS quantum dots in tetrahydrofuran solvent with quantum yields (QYs) up to 70% were synthesized using room temperature metathesis reactions. A variety of emission colors and a white spectrum from monodisperse CdS quantum dots (D~2 nm) have been demonstrated. The white emission was obtained from the CdS quantum dots directly, by altering the surface chemistry. When incorporated into an epoxy, the high solution phase QY was preserved. In contrast to other approaches, the white LED contains monodisperse CdS quantum dots, rather than a blend of different-size blue, green, and red-emitting quantum dots. The concentration of CdS quantum dots in epoxy can be increased to absorb nearly all of the incident near-UV light of the LED.

Paper Details

Date Published: 21 June 2004
PDF: 9 pages
Proc. SPIE 5366, Light-Emitting Diodes: Research, Manufacturing, and Applications VIII, (21 June 2004); doi: 10.1117/12.527967
Show Author Affiliations
Lauren E. Shea Rohwer, Sandia National Labs. (United States)
Billie L. Abrams, Sandia National Labs. (United States)
Jess P. Wilcoxon, Sandia National Labs. (United States)
Steven G. Thoma, Sandia National Labs. (United States)

Published in SPIE Proceedings Vol. 5366:
Light-Emitting Diodes: Research, Manufacturing, and Applications VIII
Steve A. Stockman; H. Walter Yao; E. Fred Schubert, Editor(s)

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