Jiasong Zhong

Direct synthesis of highly luminescent Cu–Zn–In–S quaternary nanocrystals with tunable photoluminescence spectra and decay times

We report the direct synthesis of highly luminescent Cu–Zn–In–S (CZIS) quaternary nanocrystals (NCs) in the non-coordinating solvent 1-octadecene (ODE) using chloride salts of Cu, In, and Zn as metal precursors in the presence of oleic acid and dodecanethiol. The resulting CZIS NCs had a narrow size distribution with an average diameter of 2.5 nm. The photoluminescence spectra can be tuned from 400 nm–850 nm by varying the Cuu2006:u2006Zn precursor ratio, and a relatively high photoluminescence quantum yield (PL QY) of 46% was obtained without any post-processing. The PL decay times of the as-prepared CZIS NCs were tunable via controlling the Cuu2006:u2006Zn precursor ratio and reaction time. The photoluminescence mechanism of the CZIS nanocrystals was discussed using the PL decay curves. EDS analysis revealed that the resulting CZIS NCs were Cu-deficient, and the internal defect-related emission process could be strongly promoted by the large Cu deficiency which is associated with the improvement of PL QY.

Solvothermal Synthesis and Characterization of Zinc Indium Sulfide Microspheres

Znln 2 S 4 microspheres have been solvothermally prepared at 160°C for 12 h with ZnCl 2 ·2H 2 O, lnCl 3 , and thiourea as the starting reagents in ethanol. The morphology, structure, and phase composition of the as-prepared product were characterized by means of X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectra (XPS), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and selected area electron diffraction (SAED). Results revealed that the prepared Znln 2 S 4 microspheres were composed of sheetlike nanocrystals. The average diameter of the microspheres and the thickness of the nanosheets are about 1-6 μm and 10-50 nm, respectively. A possible growth mechanism of the Znln 2 S 4 nanosheet-built microspheres was proposed and briefly discussed.

A novel green-yellow emitting phosphor Ca1.5Y1.5Al3.5Si1.5O12:Ce3+ and its luminescence properties

Abstract We described the synthesis and luminescence of Ca 1.5 Y 1.5 Al 3.5 Si 1.5 O 12 :Ce 3+ phosphor for light emitting diode (LED). The crystallinity, morphology, structure, and luminescence spectra were examined by X-ray diffraction, field emission-scanning electron microscopy and photoluminescence spectroscopy. The results showed that Ca 1.5 Y 1.5 Al 3.5 Si 1.5 O 12 :Ce 3+ phase was a dominating phase with little impurity phase peaks of Y 2 O 3 when the sintered temperature reached to 1400°C. Field emission scanning electron microscopy (FE-SEM) images showed the particle size of the phosphor was about 3 μm. Meanwhile, the excitation and emission spectra indicated that the as-prepared phosphors could be effectively excited by blue (460 nm) light and the excitation spectrum showed a broad band extending from 400–500 nm, while emission spectrum showed a broad yellow band peaking at 534 nm. The decay curve at the emission peak consisted of fast and slow components. The Ca 1.5 Y 1.5 Al 3.5 Si 1.5 O 12 :Ce 3+ should be a promising yellow phosphor for near blue-based white-light-emitting diodes (LEDs).

Synthesis and characterization of flower-like CuIn{sub 1-x}Ga{sub x}S{sub 2} (x = 0.3) microspheres

Abstract We report the formation and characterization of the flower-like CuIn 1− x Ga x S 2 ( x xa0=xa00.3) microspheres using CuCl 2 ·2H 2 O, GaCl 3 , InCl 3 and l -cystine in the mixed solvent of ethylene glycol and distilled water (1:2, v/v) at 200xa0°C for 24xa0h. XRD results indicated that the CuIn 0.7 Ga 0.3 S 2 nanostructures have a (1xa01xa02) preferred orientation. The EDS and XPS analyses of the sample revealed that Cu, In, Ga and S were present in an atomic ratio of approximately 1:0.7:0.3:2. FESEM and TEM images showed that the product was microspheres, consisting of nanoplates with the thickness of about 20xa0nm. The optical properties were investigated by ultraviolet–visible (UV–vis) absorption spectroscopy and Raman spectroscopy. UV–vis absorption spectrum indicated that the band gap of as-synthesized flower-like CuIn 0.7 Ga 0.3 S 2 microspheres was about 2.427xa0eV. Raman spectrum of the obtained CuIn 0.7 Ga 0.3 S 2 exhibited a high-intensity peak at 302xa0cm −1 could be assigned as A1-mode.