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

Abstract

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.

Optimization of the recipe for the synthesis of CuInS2/ZnS nanocrystals supported by mechanistic considerations

“…They have promising applications in solar cells [2][3][4], heat electrical application [5], light-emitting diodes (LED) [6,7], sensors [8], fluorescent probes [9,10], biolabeling [11], anticounterfeiting [12], etc. However, the intrinsic toxicity of QDs containing heavy metals (e.g.…”

Colloidal nanocrystals for quality lighting and displays: milestones and recent developments

“…Another work addressing this problem was carried out by Zhang et al, who synthesized Cu-doped InP/ZnS/InP/ZnS core/shell/shell/shell QDs [43]. These QDs also exhibited two-color emission; the Cu ions doped into the core of the QDs gave the red emission and the InP shell sandwiched between ZnS layers emitted green color.…”

Recent Progress in Quantum Dot Based White Light-Emitting Devices

“…Zhang et al [75] developed a dual-emitting system of Cu-doped CdS/ZnSe core/shell QDs, with red color originating from Cu-doped CdS and green color from recombination at the Type-II CdS/ZnSe interface. These QDs were used as color converters to fabricate WLEDs on a blue LED chip, which emitted white light with CRI of 90, CIE coordinates of (0.325, 0.330) and CCT of 5850 K. Other kinds of Cd-free doped QDs with dual emission have been used as color convertors in WLEDs as well [76][77][78]. As shown in Fig.…”

“…As shown in Fig. 9, high-quality white light (CRI 91) was realized by combining a blue LED with red and green dualemitting Cu-doped InP/ZnS/InP/ZnS QDs [76]; their emission wavelength could be tuned from visible to near infrared by carefully controlling the size of the Cu-doped InP core and the thickness of the InP quantum (Fig. 9c, d).…”

“…In all cases, the thicknesses of the quantum well barriers are three monolayer ZnS. Reproduced with permission from[76], Ó 2015 American Chemical Society…”