Light distribution and light extraction improvement mechanisms of remote GaN-based white light-emitting-diodes using ZnO nanorod array

To improve the light uniform distribution, light extraction efficiency, and phosphor conversion efficiency, both the remote phosphor coating method and the ZnO nanorod array were simultaneously utilized for fabricating the remote GaN-based white light-emitting diodes with ZnO nanorod array. Compared with the luminous flux of 1.23 lm and phosphor conversion efficiency of 74.0% of the traditional GaN-based white light-emitting diodes, the light output power and phosphor conversion efficiency of the resulting remote GaN-based white light-emitting diodes with ZnO nanorod array operated at the same injection current were improved to 1.96 lm and 89.1%, respectively. According to the measured angular distribution of the light output, the remote coating phosphor layer could make light diffusion to lead uniform light distribution. Furthermore, the ZnO nanorod array could improve the light extraction efficiency and could guide the blue light to pump the remote coating phosphor layer to convert blue light into yellow emission.

► The remote GaN LEDs with phosphor coating ZnO nanorods exhibit ideal characteristics. ► The uniform light distribution is attributed to the remote coating phosphor layer. ► The ZnO nanorod array could improve the light extraction efficiency.► The conversion efficiency of the remote GaN-LEDs achieved 89.1%.