室温下正己烷本底中PbSe量子点的荧光寿命

Photoluminescence Lifetime of PbSe Quantum Dots Doped in Hexane at Room Temperature

利用透射电镜、近红外吸收谱、荧光光谱和时间分辨光谱等技术，在室温下测量离散在正己烷有机溶剂中，不同粒径的PbSe量子点的吸收谱和荧光谱，给出了第一吸收峰和荧光峰随粒径变化的经验公式。通过对瞬态荧光衰减曲线的测量和分析，得到了PbSe量子点的荧光寿命，其寿命与量子点的表面缺陷有关。在研究的粒径范围内，由于荧光跃迁仅为带间直接跃迁和仅为缺陷态跃迁两种极端情况，可得荧光寿命最宽分布区间位于1．44～11．96μs。荧光寿命弱关联于粒径，并随粒径的增大而呈线性减小。当PbSe量子点的粒径为2．7～5．7nm时，其实测的平均荧光寿命为7．17～6．72μs。

The absorption and photoluminescence （PL） spectra of PbSe quantum dots （QDs） with different sizes and doped in organic solvent-hexane are measured by using the transmission electron microscopy （TEM）, near- infrared （NIR） absorption spectroscopy, fluorescence spectroscopy and time-resolved spectroscopy at room temperature. An empirical formula of the first absorption-peak wavelength and PL-peak wavelength varying with the size of QDs are obtained. The PL-lifetimes of PbSe QDs are determined by analyzing transient PL-decay curves. It is shown that the lifetime depends on both the surface defect and the size of QDs. The widest distribution of the lifetime ranges 1.44～11.96 μS, which can be deduced from two extreme conditions, i.e., the PL transition is only a direct interband transition and/or only a defected state transition in the range of particle size used. On the other hand, the PL lifetime is dependent weakly on the size of QDs, it will decrease with the increase of the particel size. As an example, the averaged lifetime is among 7.17～6.72 μS for the QDs diameter in the range of 2.7-5.7 nm.