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http://dx.doi.org/10.3807/JOSK.2014.18.4.370

Improvement of Light Extraction Efficiency of LED Packages Using an Enhanced Encapsulant Design  

Choi, Hyun-Su (Department of Display Engineering, Hoseo University)
Park, Joon-Sik (Department of Materials Science & Engineering, Hanbat National University)
Moon, Cheol-Hee (Department of Display Engineering, Hoseo University)
Publication Information
Journal of the Optical Society of Korea / v.18, no.4, 2014 , pp. 370-376 More about this Journal
Abstract
We optimized the design of the flat encapsulant of a light-emitting diode (LED) package to obtain higher light output power (LOP), both by experiment and simulation using three-dimensional ray-tracing software. In the experiment, the refractive index of the encapsulant was varied (1.41 and 1.53). In addition, double-layer structures with these refractive indices (1.41/1.53) were investigated by varying the shape of the interface between the two among flat, concave, and convex. The experiments showed that the LOP of the double-layer encapsulant with convex interface increased by 13.4% compared to the single-layer encapsulant with a refractive index 1.41, which was explained by the increase of the light extraction efficiency (LEE) in connection with the increase of the critical angle (${\theta}_c$) and the decrease of the Fresnel reflection.
Keywords
Light-emitting diode (LED); Encapsulant; Light extraction efficiency (LEE); Fresnel reflection; 3-D ray-tracing simulation;
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