Combined Experimental and Monte-Carlo Ray-Tracing Approach for Optimizing Light Extraction in LED COB Modules

Abstract

High-power light-emitting diodes (LEDs) for lighting applications require a high-efficient packaging to optimize their performances. Due to its high thermal dissipation potential, the chip-on-board (COB) technology is widely used for developing high-power lighting sources. In order to optimize the optical properties of such sources and to propose high optically efficient encapsulation geometry, ray-tracing simulations have been performed. The impact of the shape and volume of the silicone encapsulation on the light extraction and on the intensity distribution of the module was derived. Then, simulation results were correlated with experimental measurements on blue light-emitting COB sources. It is shown that a nearly hemispherical encapsulation with a minimal volume of 5 to 10 mm3 for a 1 mm2 LED die is the optimal configuration regarding both the light extraction and the intensity distribution.

Spectral dependence of light extraction efficiency of high‐power III‐nitride light‐emitting diodes

“…increase in the LED efficiency due to casting of the LED chip by a transparent material with the refractive index higher than that of air. The method is based on preliminary simulations to find a correlation between EG and η ext , which is known to depend on the chip size, encapsulant shape , and other details of the LED design . Being accurate enough, the simulations may, however, predict η ext by themselves, making the experiments unnecessary.…”