Colour-crafted phosphor-free white light emitters via in-situ nanostructure engineering

Colour-temperature (T_c) is a crucial specification of white light-emitting diodes (WLEDs) used in a variety of smart-lighting applications. Commonly, T_c is controlled by distributing various phosphors on top of the blue or ultra violet LED chip in conventional phosphor-conversion WLEDs (PC-WLEDs). Unfortunately, the high cost of phosphors, additional packaging processes required, and phosphor degradation by internal thermal damage must be resolved to obtain higher-quality PC-WLEDs. Here, we suggest a practical in-situ nanostructure engineering strategy for fabricating T_c-controlled phosphor-free white light-emitting diodes (PF-WLEDs) using metal-organic chemical vapour deposition. The dimension controls of in-situ nanofacets on gallium nitride nanostructures, and the growth temperature of quantum wells on these materials, were key factors for T_c control. Warm, true, and cold white emissions were successfully demonstrated in this study without any external processing.