Various nanofabrication approaches towards two-dimensional photonic crystals for ceramic plate phosphor-capped white light-emitting diodes

This paper compares four different nanofabrication processes towards various two-dimensional (2D) photonic crystals (PCs) on a Y3Al5O12:Ce3+ (YAG:Ce) yellow ceramic plate phosphor (CPP) in order to enhance the luminous efficacy of YAG:Ce CPP-capped high-power white light-emitting diodes (LEDs). Compared with conventional flat CPP-capped LEDs, every type of 2D PC-assisted YAG CPP-capped LED improves the outcoupling efficiency, current and temperature stability, angular stability of color temperature, and thermal conductivity. Careful evaluation of the optical properties of 2D PC-assisted CPP LEDs shows that the highest luminous efficacy (similar to 142.7 lm W-1) is attained from a 2D TiO2 nanobowl PC-CPP LED sample, which was fabricated by nanosphere-based template growth and the dry etching process, and this evaluation indicates that 2D PC-assisted CPP-capped white LEDs will lead to further technological advancements for applications in highly efficient and thermally stable high-power white LEDs.