Improvement in optical performance of white light-emitting diodes using randomly textured phosphor-in-glass

To enhance light extraction efficiency and light quality of white light-emitting diodes (WLEDs), a randomly textured phosphor-in-glass (PiG), which can be fabricated by chemical wet-etching and screen-printing methods, is proposed. The performance of WLED with textured PiG is examined by experiments. Measurement results reveal that the luminous flux of WLED package with textured PiG increases by 4.6% compared that with flat PiG package. The increment is attributed to the fact that the roughened surface can reduce the total internal reflection (TIR) at the interface between air and PiG, leading to the enhancement of light extraction efficiency. Meanwhile, the textured PiG package reduces angular correlated color temperature (CCT) deviation from 1759K to 968K in the viewing angles of −75° to 75°, when the average CCT is about 5500K. With simplified process, low cost and superior optical properties, the textured PiG is expected to be a promising candidate for applications in solid-state lighting.