Abstract
Quantum dots (QD) are semiconductor nanocrystals with quantum confinement of charges carried in limited spaces. They are expected to have high quantum yield, photo and thermal stability, and strongly size dependent emission wavelength. Non-blinking CdTe QDs have been synthetized in water phase by microwave irradiation with mercaptopropionic acid as a stabilizer. They exhibit high QY, good photo and chemical stability in water solution. QD with sizes from 2.1nm to 5nm have been studied. Time-resolved photoluminescence (PL) decays were measured by TCSPC technique upon one and two photon excitation (2PE). The effect of temperature and pH on PL decay was studied at several excitation wavelengths. Lifetime distribution, extracted from PL decay by Maximum Entropy Method of data analysis, display up to five components. PL decay of small QD is slower at longer wavelength (figure). The lifetime distribution of the larger QDs always exhibits three lifetime peaks around 15 ,37 and 100ns respectively , only relative contributions of each peak vary with size.View Large Image | View Hi-Res Image | Download PowerPoint Slide
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