| Summary: | 碩士 === 國立臺灣科技大學 === 化學工程系 === 97 === In this study, CdSeS quantum dots (QDs) were synthesized via non-coordinated system. The structural model of CdSeS QDs was established by using composition analysis, absorption spectroscopy and emission spectroscopy. When the molar ratio of II group element and VI group element was employed to control the structure of CdSeS QDs, we found that CdSeS QDs would precipitate easily if VI group element was excess and CdSeS QDs with high photoluminescence quantum yield (PL QY) could be produced if II group element was excess. In addition, the emission wavelength and PL QY could be modulated by controlling the composition ratio of Se and S in the injection stock solution. The emission wavelength of CdSeS QDs shifts to short wavelength and PL QY could also increase with increasing the composition of S. The results demonstrated that the band gap of CdSeS QDs was not only tunable with size, but also with composition of reactant.
In the study, we also used composition analysis, size distribution and absorption spectroscopy to speculate the structural model of CdSeS QDs by gradient or core-shell model successfully. Additionally, the influence of different surfactants on the recombination of electron-hole pairs inside the CdSeS QDs was also be discussed. When suitable surfactant was chose to passivate the surfaces of CdSeS QDs, PL QY could increase to 91%.
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