Effect of Amorphous Photonic Structure Surface Mounted on Luminous Performances of White LED

Abstract

We fabricated amorphous photonic structures (APSs) with different periods and hole diameters. The GaN-based white light emitting diodes (LEDs) at nominal correlated color temperatures (CCTs) of 5000 and 6000 K were surface mounted by these APSs. The electroluminescence (EL) measurements showed less luminous efficiency (LE) and higher CCT than the ones of the virginal white LEDs. However, the LEs of many APS-mounted white LEDs increased compared to white the LEDs without APSs at the same CCTs. A finite-difference time-domain (FDTD) simulation was carried out on the ASPs surface-mounted white LEDs and bidirectional scattering distribution functions (BSDFs) of different emissions were transferred to a Monte Carlo ray tracing simulation. The simulated LEs and CCTs conformed well to the experimental ones. The effects of the blue emission transmission and phosphor concentration were simulated to predict the absolute LE enhancement methods for white LEDs. At last, the hopeful APSs for high Les’ general lighting were discussed.

Keywords

• white light emitting diode (WLED)
• amorphous photonic structure (APS)
• luminous efficiency (LE)
• correlated color temperature (CCT)
• Fresnel loss
• finite-difference time-domain (FDTD)