Department of Applied Physics, Graduate School of Engineering, Osaka City University, 3-3-138, Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan.
Phys Chem Chem Phys. 2013 Dec 28;15(48):21051-7. doi: 10.1039/c3cp54012j.
We have investigated the temperature dependence of photoluminescence (PL) dynamics of self-assembled monolayers (SAMs) of CdSe quantum dots (QDs). The PL decay profiles become slower with an increase in temperature up to 160 K, contrary to an ordinary behavior due to thermal quenching. Such anomalous temperature dependence of the PL-decay profile is explained using a four-state model which introduces a bound-exciton state into a conventional three-state model consisting of a ground state and two excited states: a lower-lying dark-exciton state and a higher-lying bright-exciton state. Furthermore, it is proposed that the radiative decay time of QDs is strongly influenced by the presence or absence of the bound-exciton state.
我们研究了自组装单层 CdSe 量子点 (QD) 的光致发光 (PL) 动力学随温度的变化。PL 衰减曲线随温度升高至 160 K 而变慢，这与由于热猝灭而导致的普通行为相反。通过引入一个束缚激子态到由一个基态和两个激发态组成的常规三态模型中，可以解释 PL 衰减谱的这种反常温度依赖性：一个较低的暗激子态和一个较高的亮激子态。此外，有人提出，QD 的辐射衰减时间受到束缚激子态的存在与否的强烈影响。
