[23a-P06-1~28] 21 Joint Session K "Wide bandgap oxide semiconductor materials and devices"(Poster)

▲ [23a-P06-20] White light emitting diodes based on ZnO nanoparticles using phosphors

〇(D)RAJ DEEP¹, Akazawa Takuma¹, Toshiyuki Yoshida¹, Yasuhisa Fujita¹ (1.Shimane University)

Keywords:White LED, ZnO Nanoparticles, UV Electroluminescence

White light-emitting diodes (WLEDs) have become the next-generation solid-state lighting sources owing to their advantages of energy conservation, long lifetime, and high luminous efficiency. Currently, white LEDs produced from GaN-based blue LEDs with yellow phosphor have problems of poor color rendering and high fabrication costs due to the use of single-crystal substrates and sophisticated vacuum equipment. To mitigate this problem, our group created nitrogen-doped ZnO nanoparticles (NPs) based UV-LEDs by spin coating p-ZnO NPs on GZO film. The UV emission was realized and fabricated. In this study, white light emitting diodes were fabricated using multi-phosphor approach method. Phosphor-converted white light-emitting diodes were fabricated by precoating blue/green/red phosphors onto near UV based ZnO nanoparticle-based LEDs.
With optimized phosphor blend, white light was realized, and electro-luminescence spectra is plotted. White light with near-ideal Commission International de l’Eclairage (CIE) coordinates (x = 0.3163, y = 0.3281 at λex = 380 nm) and correlated color temperature (CCT) of 6317 K (corresponding to day white-light). WLEDs exhibited excellent color rendering index (CRI) Ra ~ 90, variable with phosphor blend. When the injection current was increased from 45 to 60 mA, less variation in CCT and CRI was also observed, indicating better optical stability than conventional “blue + yellow” white LEDs.