以聚酰胺-胺树形分子为模板制备了平均粒径为2.5nm的CdS量子点, 采用HRTEM、EDS、UV-vis、PL等手段对样品进行表征, 研究了其在室温避光条件下的老化过程. 结果表明, CdS量子点在刚制备的前5d里UV-vis、PL谱峰半峰宽变窄, 发光效率迅速上升, 表明量子点以尺寸窄化生长为主; 5d后UV-vis、PL谱峰半峰宽逐渐宽化, 发光效率缓慢下降, 表明量子点以尺寸宽化(Ostwald 熟化)过程为主. 树形分子的配位作用和模板作用赋予CdS量子点良好的抗老化性能, 6个月后量子点粒径增量<0.3nm, PL强度约降低22%.
CdS quantum dots (QDs) of 2.5nm were prepared using G4.5 PAMAM dendrimer templates and characterized by HRTEM and EDS. The aging of synthesized QDs stored in the dark at room-temperature was studied through UV-vis and PL spectrophotometer. The width at half-maximum of the peak (WHM) of the UV-vis and PL spectra becomes narrower, meanwhile the PL intensity increases obviously during the first 5d. Afterwards, the WHM gets broader and the PL intensity decreases slowly during the following 6 months. The results suggest that CdS QDs show a size-focusing growth within the first 5d, but a size-defocusing growth in the following 6 months. However, the increment of CdS QDs size is less than 0.3nm, and the decrement of PL intensity is about
22% after 6 months of aging. The excellent resistance to aging of CdS QDs is attributed to the coordination and template effects of PAMAM dendrimers.
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