Synthesis, optical and X-ray difractometry charactericrics of ZnO colloidal quantum dots
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GERU, Ion, MIDONI, Irina, VOLODINA, Galina. Synthesis, optical and X-ray difractometry charactericrics of ZnO colloidal quantum dots. In: Achievements and perspectives of modern chemistry, 9-11 octombrie 2019, Chişinău. Chisinau, Republic of Moldova: Tipografia Academiei de Ştiinţe a Moldovei, 2019, p. 101. ISBN 978-9975-62-428-2.
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Achievements and perspectives of modern chemistry 2019
Conferința "International Conference "Achievements and perspectives of modern chemistry""
Chişinău, Moldova, 9-11 octombrie 2019

Synthesis, optical and X-ray difractometry charactericrics of ZnO colloidal quantum dots


Pag. 101-101

Geru Ion1, Midoni Irina1, Volodina Galina2
 
1 Institute of Chemistry,
2 Institute of Applied Physics
 
Disponibil în IBN: 5 noiembrie 2019


Rezumat

The semiconducting ZnO colloidal quantum dots are an important topic of research due to their applications in different areas such as biological systems and optoelectronic devices (LEDs, solar cells, and gas sensors) [1-4]. ZnO quantum dots are characterized by reduced degree of toxicity as compared to other II-VI, III-V, and IV-VI nanoparticles. These are therefore particularly promising in medical applications.The lines of X-ray diffraction for ZnO colloidal quantum dots (DRON-UM1, diffractometer, FeKa radiation, Mn filter).Figure 2.UV-Vis absorption spectra of ZnO colloidal quantum dots in methanol.The ZnO quantum dots have been synthetized from a methanol based solution that was prepared by mixing the zinc acetate (Zn(O2CCH3)2, ZnAc), and methanol. After this, the water was added in this mixture in such a way that a ZnAc/H2O molar ratio of 0.2 was reached, and triethanolamine (C6H15NO3, TEA) was added too. The reaction mixture was stirred at 60°C during 60min. Subsequently, water was added to produce the precipitation. Afterwards, the white powder was separated by centrifugation, washed several times in methanol and dried at 100°C during 1 h. Due to large values of the free surface energy, the ZnO quantum dots are characterized by a high degree of reactivity. In particular, using TEA as a surfactant canlead to the increase in quantum efficiency of photoluminescence. Based on X-ray diffraction data (Figure 1), it was shown that the obtained ZnO nanocrystals of hexagonal symmetry have sizes of ~13 nm along the c axis and ~9 nanometers in the orthogonal direction. The UV-Vis spectra of ZnO quantum dots (Figure 2) show a 1S exciton peak at about 373 nm. When the concentration of nanoparticles in methanol is increasing (down up, mg/mL: 2.6, 3.0, 3.5, 5.4), the peak shows a multiplete structure at the concentration c = 5.4 mg/mL (a sludge solution).