Aqueous Synthesis of CdTe Quantum Dots via Ascorbic Acid Reducing Sodium Tellurite†

doi:10.7503/cjcu20141079

Abstract

Abstract:

Cd-SCH₂COO^- complex was formed under basic condition, then the ascorbic acid reacted with Na₂TeO₃ to form Te^2- ions that combined with Cd-SCH₂COO^- complex to give CdTe nucleus. With the CdTe nucleus growing under refluxing, CdTe quantum dots(QDs) with different emission colors were formed at last. The influence of experimental conditions, including refluxing time, thioglycolic acid to cadmium molar ratio and sodium tellurite to cadmium molar ratio, on the luminescent properties of the obtained CdTe QDs were systematically investigated. Furthermore, the obtained QDs were characterized by X-ray powder diffraction(XRD) and transmission electron microscopy(TEM). Experimental results showed that the proposed method enables us to obtain zinc-blended CdTe QDs with high photoluminescence quantum yield(up to 27.1%). The growth time and the relative quantities of reactants impacted the optical properties of QDs.

Key words: CdTe quantum dots, Optical property, Luminescence

CLC Number:

O611.4

TrendMD:

XIE Xian, YU Meihua, ZHANG Huiping, WANG Yilin. Aqueous Synthesis of CdTe Quantum Dots via Ascorbic Acid Reducing Sodium Tellurite^†[J]. Chem. J. Chinese Universities, 2015, 36(4): 608.

Figures/Tables 7

Scheme 1 Formation of CdTe QDs

Fig.1 Absorption(A) and photoluminescence(B) spectra for a series of CdTe QDs prepared at pH=10.5, n(Cd):n(Te):n(TGA)=2:0.10:4.2 for different refluxing time Reflux time/min: a. 10; b. 30; c. 120; d. 300; e. 480. Inset of (A) shows the relationship between particle size and reflux time.

Fig.2 Normalized absorption and photoluminescence spectra of CdTe QDs solution before(solid line) and after(dashed line) being aged for 8 months

Fig.3 XRD pattern of CdTe QDs prepared at pH=10.5, n(Cd):n(Te):n(TGA)=2:0.10:4.2, refluxed for 480 min

Fig.4 TEM(A), HRTEM(B) images and SAED pattern(C) of as-synthesized CdTe QDs

Fig.5 Influences of various TGA/Cd molar ratios on photoluminescence spectra of CdTeQDs prepared at pH=10.5n(Te):n(Cd)=0.1:2. n(TGA)/n(Cd): (A) 3.5/2; (B) 4.9/2; (C) 5.6/2; (D) 6.3/2. Reflux time/min: a. 10; b. 30; c. 120; d. 300; e. 480.

Fig.6 Influences of various Te/Cd molar ratios on photoluminescence spectra of CdTe QDs prepared at pH= 10.5 n(TGA):n(Cd)=4.2:2. n(Te)/n(Cd): (A) 0.05/2; (B) 0.15/2. Reflux time/min: a. 10; b. 30; c. 120; d. 300; e. 480.

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