Silica-Coated ZnS Quantum Dots for Multicolor Emission Tuning from Blue to White Light

Abstract

The present work reports the easy tunability from blue to cold-white light emission of ZnS quantum dots embedded into a silica matrix (ZnS@SiO 2 ) by simple heating treatments (up to 900 °C) without the need of rare earth or heavy metal ion doping. The heating causes gradual changes in the composition of samples, such as crystallization of cristobalite and formation of zinc silicate, whose optical properties contribute to the tunability of the material. The evolution of the induced changes in the shape and structure was followed by scanning electron microscopy, Xray diffraction, X-ray photoelectron spectroscopy, and Raman and Fourier transformed infrared spectroscopies. Diffuse reflectance and photoluminescence spectroscopies were used to analyze the optical properties of the obtained materials, exhibiting that as-synthesized ZnS@SiO 2 nanoparticles have an intense and wide blue emission band centered around 440 nm under 325 nm excitation, which is modified by the temperature with the enhancement of the intensity and widening of the band emission, as well as maximum shifting. The calculations of the CIE 1931 chromaticity coordinates show the tuning of the precepted tonality of the emission color from ocean-blue (0.18, 0.14) up to blue-sky (0.20, 0.31) and cold white light (0.27, 0.33) with a correlated color temperature of 12 500 and 7400 K for the last two. Besides suitable and facile tuning of the color emission, the thermal treatment of samples increases the stability of each one allowing their long-term usage as emitting devices.

Monodisperse colloidal spheres with a high refractive index: their synthesis, assembly and application in structural colored materials

“…(1) Zinc sulfide (ZnS) spheres. ZnS is a widely applied metal sulfide with various important technological applications, such as pigment, [51][52][53] electroluminescence materials, 54,55 anode materials of batteries, 56 infrared windows [57][58][59] and solar cells. [60][61][62] The relatively high refractive index of its bulk material (B2.36 for cubic phase ZnS) and their transparency in the visible region make it an ideal candidate as building blocks for PCs.…”

Enhanced Luminescence of Dye-Decorated ZIF-8 Composite Films via Controllable D–A Interactions for White Light Emission

“…In this sense, it is necessary to develop emerging luminescent materials. Until now, many luminescent materials such as rare-earth materials, − organic fluorescent dyes, − perovskites, − quantum dots, − metal–organic frameworks (MOFs), ,, and carbon dots − have shown great potentials in structure versatility, wavelength tunability, and short luminescence lifetimes and have been used in white LEDs.…”