University of PardubiceFaculty of Chemical Technology

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The effect of temperature in synthesis of gradient alloyed CdSe0.2S0.8 quantum dots

Authors: Plaček Patrik | Loghina Liudmila | Šlang Stanislav | Pálka Karel | Vlček Miroslav

Year: 2018

Type of publication: ostatní - přednáška nebo poster

Page from-to: nestránkováno

Titles:

Language	Name	Abstract	Keywords
eng	The effect of temperature in synthesis of gradient alloyed CdSe0.2S0.8 quantum dots	The synthesis of high-quality semiconductor quantum dots (QDs) has been investigated in the last 20 years since the first synthesis of CdSe QDs by Murray et al. [1]. The direct dependence of the optical characteristics of QDs, their sizes and shapes was established for binary compositions CdS and CdSe [2]. In the current study, we present our results of temperature effect in the synthesis of ternary gradient alloyed CdSe0.2S0.8 QDs. The described [3] technique was implemented this synthesis, where CdO was used as source of Cd, trioctylphosphine sulfide and trioctylphosphine selenide were used as Se and S precursors, respectively. Experiments started at 300 °C as the most frequently used temperature for hot-injection synthesis, and the temperature was decreased with 20 °C step down to 200 oC. The nucleation and growth of QDs were studied by UV-VIS and photoluminescence spectroscopy. The structure and composition of synthetized CdSe0.2S0.8 QDs were characterized by X-Ray crystallography, X-ray photoelectron spectroscopy (XPS), STEM and EDS. It was found that QDs synthetised at high temperature (300 °C) tend to aggregate and their growing rate has been very fast. Furthermore, due to different S and Se precursors reactivity the significant changes in chemical compositions have been observed. EDS analysis also proved the S/Se, Cd/S,Se ratios were instable in this case. It was found that suitable temperature for synthesis of studied QDs was in the temperature between 200 °C and 240 °C, with growing time of 1 hour. QDs synthesized at 220 °C exhibit the highest photoluminescent quantum yield (PLQY up to 80%) and almost targeted Cd/S,Se ratio.	synthesis; semiconductors; quantum dots; gradient alloy Cd-S-Se; temperature