High color rendering index and tunable color temperature of white light emitting diodes with yellow emitting graphene quantum dots coated

In this work, we report the hydrothermal synthesis of yellow emitting graphene quantum dots (GQDs). The as prepared GQDs were fixed in polymer-silica hybrid matrix, deposited on InGaN blue chip and formed as transparent flexible color conversion layer of white light emitting diodes (WLED). The properties of GQDs and devices were also investigated, and we found the GQDs exhibit stable fluorescence in the ethanol solution. The as prepared GQDs WLED shows extremely high color rendering index (CRI) reaching up to 92. And in this work we realized the correlated color temperature (CCT) tunable (from 3200K to 9200K) by adjusting the thickness of GQDs color conversion layer or the concentration of GQDs solution. The color coordinates of WLEDs distribute close to the Planckian locus. These results indicate that the GQDs might be a promising candidate as yellow-emitting phosphor for white LEDs.