Nanocrystal integrated light emitting diodes based on radiative and nonradiative energy transfer for the green gap

Date
2009
Advisor
Instructor
Source Title
2009 IEEE LEOS Annual Meeting Conference Proceedings
Print ISSN
1092-8081
Electronic ISSN
Publisher
IEEE
Volume
Issue
Pages
75 - 76
Language
English
Type
Conference Paper
Journal Title
Journal ISSN
Volume Title
Abstract

Recently the photometric conditions for ultra-efficient solid-state lighting have been discussed [1-2]. These studies show that a luminous efficacy of optical radiation at 408 lm/Wopt and a color rendering index (CRI) of 90 at a correlated color temperature (CCT) of 3000 K are achievable at the same time. For this purpose light emitting diodes (LEDs) emitting in blue, green, yellow, and red colors at 463, 530, 573, and 614 nm with relative optical power levels of 1/8, 2/8, 2/8, and 3/8, are required, respectively [1-2]. Although InxGa1-xN material system is capable to cover the whole visible by changing the In composition (x), it is technically extremely challenging to obtain efficient green/yellow light emitting diodes especially at those wavelengths (i.e., at 530 nm and 573 nm, respectively) due to reduced internal quantum efficiency [2-4]. Furthermore, by using the (Al xGa1-x)1-yInyP quaternary alloy it is also possible to cover from 650 nm to 580 nm. However, the efficiencies significantly decrease towards green. Therefore, there exists a significant gap in the green-yellow spectral regions (known as "the green gap") to make efficient light emitting diodes. To address this green gap problem, we propose and demonstrate proof-of-concept nanocrystal (NCs) hybridized green/yellow light emitting diodes that rely on both radiative energy transfer and nonradiative energy transfer (i.e., FRET-Förster resonance energy transfer) for color conversion on near-ultraviolet (near-UV) LEDs.

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Other identifiers
Book Title
Keywords
Color conversions, Color rendering index, Correlated color temperature, Green-yellow spectral region, Internal quantum efficiency, Luminous efficacy, Material systems, Nonradiative energy transfer, Optical power, Optical radiations, Proof of concept, Quaternary alloys, Radiative energy transfer, Resonance energy transfer, Solid state lighting, Color, Diodes, Energy transfer, Gallium, Light emission, Nanocrystalline alloys, Nanocrystals, Quenching, Light emitting diodes
Citation
Published Version (Please cite this version)