Spectral conversion with fluorescent microspheres for light emitting diodes

– KN Hui, PT Lai, and HW Choi

Schematic diagram of microsphere-array coated hexLED.

Optics Express, vol. 16, 1, pp. 13-18 (2008)

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.

DOI: 10.1364/OE.16.000013