采用紫外-可见-近红外分光光度计和稳态/瞬态荧光光谱仪,分别测量了离散在水溶液中的CdS_xSe_1-x/ZnS量子点的吸收-辐射荧光谱以及及荧光强度随时间的变化,得到了荧光寿命随粒径、x和温度的变化。荧光寿命主要取决于量子点带间的直接跃迁,缺陷态间接跃迁的影响为次。得到了荧光峰值波长和荧光寿命随粒径、x变化的经验公式。结果表明:荧光寿命随粒径增大而增大,随S组分增加而减小,且对温度的变化不敏感;当量子点粒径为4.06~9.22 nm、x为9.45~0.366、温度为15~55 ℃时,荧光寿命为2.51~3.22 μs。

The absorption-emission spectra of CdSxSe1-x/ZnS quantum dots (QD) dispersed in the aqueous solution and their photoluminescence (PL) intensities varying with time are measured using an ultraviolet-visible-near infrared spectrophotometer and steady state/transient PL spectrometer, respectively. The variation in the PL lifetime with the QD size, x, and temperature is obtained. The measured PL lifetime is mainly decided by the interband-direct transition of QD, and the indirect transition of defect states is the second factor. Empirical formulas are presented for PL-peaking wavelength and PL lifetime depending on the QD size and x. The results demonstrate that the PL lifetime increases as the increasing particle size and decreases as the increasing proportion of the S component. However, it is insensitive to temperature. The measured PL lifetime is approximately 2.51-3.22 μs for the QDs with the size of 4.06-9.22 nm when the x is 9.45-0.366 and the temperature is 15-55 ℃.