High Color Rendering White-light-emitting Diodes Based on Cu-doped ZnInS and ZnCdS Quantum Dots

Cu-doped quantum dots( QDs) were used as color converting materials for preparing efficient white light-emitting diodes( LEDs). The Cu-doped QDs synthesized by chemical method showed composition-tunable emission from green to deep red and large Stokes shifts. By using the combination of green light-emitting Zn In S∶ Cu QDs and red emitting Zn Cd S∶ Cu QDs with blue Ga N chips,a high color rendering white LED was fabricated. The resulting three-band RGB QD-white LED exhibits high performance with luminous efficacy of 71 lm / W,color rendering index up to 94,CIE-coordinates of( 0. 352 4,0. 365 1),and color temperature of 4 788 K. Based on the changes in the photoluminescence lifetimes of Cu-doped QDs,it is found that the energy transfer process from green Zn In S∶ Cu QDs to red Zn Cd S∶ Cu QDs can be negligible,because the red QDs had no absorption at green band. These results suggest that Cu-doped QDs are promising for solid state lighting.