Large-scale synthesis of single-source, thermally stable, and dual-emissive Mn-doped Zn–Cu–In–S nanocrystals for bright white light-emitting diodes

Abstract

Non-cadmium" dual emissive QDs have been directly synthesized using a one-pot hot-injection technique. A white LED was successfully fabricated using a commercial blue-LED chip combined with the optimal QDs. ABSTRACTThe global demand for resource sustainability is growing. Thus, the development of single-source environment-friendly colloidal semiconductor nanocrystal (NC) phosphors with broadband emission is highly desirable for use as color converters in white light-emitting diodes (WLEDs). We report herein the gram-scale synthesis of single-source, cadmium-free, dual-emissive Mn-doped Zn-Cu-In-S NCs (d-dots) by a simple, non-injection, and low-cost approach in one-pot fashion. This synthesis approach led to the formation of NCs with continuously varying compositions in a radial direction because the reactivity of precursors totally differed among these precursors. Consequently, d-dots exhibited two emission bands, one of which was due to Mn-related emissions and the other was due to the band edge of Zn-Cu-In-S NCs. Emission peaks assigned to band edge were tunable by simple control of particle size and composition. The prepared d-dots also exhibited the characteristic zero self-absorption, a quantum yield of 46%, and good thermal stability. A combination of a commercial blue LED chip with optimal d-dots as color converters gave a high color rending index of up to 90, Commission International de l'Eclairage color coordinates of (0.332, 0.321), and correlated color temperature of 5680 K. These results suggested that this cadmium-free, excellent thermally stable single-phase d-dot phosphor had potential applications in WLEDs. Nano Research DOI () Research Article| www.editorialmanager.com/nare/default.asp 2 Nano Res.

Red‐Tuned Mn d–d Emission in Doped Semiconductor Nanocrystals

“…Colloidal stability and emission stability have also been achieved, and these materials have been commercialized. These materials are also thermally stable, and in colloidal solution bright emission has been observed even at 250 °C ,. Figure shows a digital image of water‐soluble Mn‐doped ZnS nanocrystals dispersed in boiling water in air, which highlights the significant achievements made in the synthesis and surface modification of these doped nanocrystals.…”

Bandgap‐ and Radial‐Position‐Dependent Mn‐Doped Zn–Cu–In–S/ZnS Core/Shell Nanocrystals

“…[41] In our previousw ork, we successfully prepared dualemissive NCs by controlling the dopant positioni nM n-doped Zn-Cu-In-S QDs. [42] However, these experimental data still lack the answer on whether/how dopantp ositions inside core/shell QDs or host compositions affect the optical properties of doped core/shell multinary QDs.…”

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.…”

“…Dual color Mn-doped CIS/ZnS QDs with green and orange emission were integrated on blue LED chips, to realize WLEDs with CRI of 83 and LE of 61 lm/W [77]. In a recent study, an optimized non-injection method was developed to produce such Mn-doped QDs on a large scale [78], which were used to produce WLEDs with high CRI of 90 and CIE coordinates of (0.332, 0.321). Several kinds of white-emitting nanocrystals have been reported so far, such as trap-rich CdS QDs [79][80][81][82][83], magic-sized CdSe QDs [84][85][86][87][88], alloyed Zn x Cd 1-xSe(S) QDs [89,90], onion-like CdSe/ZnS/CdSe/ZnS QDs [80], and ZnSe QDs [91,92].…”