| SM ISO690:2012|
TURTA, Constantin; BORDIAN, Olga; LOSHMANSKY, Constantin; CULEAC, Ion; TURTA, Constantin. Synthesis and characterization of CdSe colloidal quantum dots in organic solvents. In: The International Conference dedicated to the 55th anniversary from the foundation of the Institute of Chemistry of the Academy of Sciences of Moldova. 28-30 mai 2014, Chișinău. Chișinău, Republica Moldova: Institutul de Chimie al AȘM, 2014, p. 21.
|The International Conference dedicated to the 55th anniversary from the foundation of the Institute of Chemistry of the Academy of Sciences of Moldova 2014|
Conferința "The International Conference dedicated to the 55th anniversary from the foundation of the Institute of Chemistry of the Academy of Sciences of Moldova" |
Chișinău, Moldova, 28-30 mai 2014
Among various semiconductor quantum dots (QDs) extensive research efforts have been developed over the last decade in case of CdSe QDs because of their attractivity for various application in optoelectronics, photonics, medicine, etc. In this report we present experimental results on synthesis and characterization of colloidal CdSe quantum dots, prepared by a modified hot injection technique. The obtained CdSe QDs were further isolated and purified by adding acetone to the cooled solution followed by centrifugation. CdSe QDs have been characterized by UV-Vis absorption and photoluminescent (PL) spectroscopy. The average CdSe particles size for three selected samples was estimated from the position of first excitonic peak in the UV-Vis absorption spectrum (Fig. 1), and was found to be in the range 2.28-2.92 nm which is in good agreement with PL experimental data. The size of CdSe quantum dots for the selected samples 1, 2, 3 was varied by changing the reaction duration and represent 2.28, 2.42 and 2.92 nm respectively. The PL emission spectra have been registered at room temperature in photon counting regime under the excitation of laser beam 405 nm. The PL spectrum for CdSe nanocrystals is dominated by near-band-edge emission, while a weak broad band related to the surface shallow trap emission is substantialy suppressed (Fig. 2,3). The narrow line width (24 nm) of the main PL band (Fig. 3) suggests the nanoparticles having narrow size distribution. Alternatively, low intensity emission from surface trap states observed at longer wavelengths, indicates on some concentration of surface defects because of lack of surface passivation. On the other side, no PL emission from surface trap states at longer wavelengths were observed for sample 3, apparently suggesting no surface defects. PL spectra of CdSe dots are red-shifted as the core size increases, with the maxima of PL band at 508.8 nm, 543.9 nm and 566 nm.