Open AccessSpectral conversion with fluorescent microspheres for light emitting diodes
Author(s) -
Kwun Nam Hui,
P.T. Lai,
H. W. Choi
Publication year - 2008
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.16.000013
Subject(s) - materials science , fluorescence , luminous efficacy , optics , light emitting diode , microsphere , diode , optoelectronics , coating , white light , fluorescent lamp , luminous flux , color temperature , green light , light source , blue light , nanotechnology , layer (electronics) , physics , engineering , chemical engineering
An innovative spectral conversion scheme for light emitting diodes using fluorescent microspheres has been demonstrated. An optimally mixed proportion of green and red fluorescent microspheres were coated onto a high-extraction-efficiency GaN micro-LED with emission centred at 470 nm. The microspheres self-assemble into ordered hexagonally arrays, forming regular and uniform coating layers. Devices with cool and warm white emission were achieved. The bluish-white LED has a luminous efficacy of 27.3 lm/W (at 20 mA) with CIE coordinates of (0.26, 0.28) and 8500K CCT, while the yellowish-white LED has a luminous efficacy of 26.67 lm/W (at 20 mA) with CIE coordinates of (0.36, 0.43) and 13000K CCT.