Dual Emissive Cu:InP/ZnS/InP/ZnS Nanocrystals: Single-Source Greener Emitters with Flexibly Tunable Emission from Visible to Near-Infrared and Their Application in White Light-Emitting Diodes

Single-phase greener phosphor with broadband emission made of colloidal quantum dots (QDs) is most desirable for use as color convertors in white light-emitting diodes (WLEDs). Here, we demonstrate a single cadmium-free component system consisting of Cu-doped InP core/ZnS barrier/InP quantum well/ZnS shell QDs, which exhibits two emission peaks by controlling the barrier thickness under single-excitation wavelength, one of which being attributed to Cu-doped InP, and the other resulting from InP quantum well. The dual emissive peaks were successfully tuned in a range from visible to near-infrared by simple control of the core size and the well thickness, respectively. Using optimal structures as color converters, we successfully obtained WLED with a color rending index (CRI) up to 91 and CIE color coordinates of (0.338, 0.330) by combination with blue LED chip, indicating this single-phase phosphor with great promise for use in solid-state lighting due to flexibly tunable dual emission peak position in the entire visible region.