Photobrightening and photodarkening in PbS quantum dots
Photobrightening and photodarkening in PbS quantum dots
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DOI：
10.1039/b604743b
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发表时间：
2006-01-01
影响因子：
3.3
通讯作者：
Krauss, Todd D.
中科院分区：
文献类型：
--
作者：
Peterson, Jeffrey J.;Krauss, Todd D.
利用荧光光谱研究了不同环境条件下PbS量子点的光变暗和光增亮行为。我们能够区分电荷捕获、长寿命光学暗态(单粒子荧光闪烁)和不可逆光氧化对整体光变暗行为的贡献。这两个过程都产生了对以排放为基础的技术应用可能有害的影响。电荷捕获是短时间尺度上的主要机制(<；3 S)，不表现出颗粒大小或环境依赖，是可逆的，并且比CdSe量子点快一个数量级。在长时间尺度(50-100 S)上，光氧化是占主导地位的机制，强烈依赖于颗粒大小和环境大气，导致发射强度不可逆转地降低，发射最大值显著蓝移，颗粒分布增加。
Fluorescence spectroscopy is utilized to investigate photodarkening and photobrightening behaviors in PbS quantum dots (QDs) subjected to various environmental conditions. We are able to separate contributions from charge trapping to a long-lived optically dark state (single particle fluorescence blinking) and irreversible photooxidation to the overall photodarkening behavior. Both processes produce effects that are potentially detrimental for emission-based technological applications. Charge trapping is the dominant mechanism on short time scales (< 3 s), exhibits no particle size- or environmental-dependence, is reversible, and is an order of magnitude faster compared to CdSe QDs. Photooxidation is the dominant mechanism on long time scales (50-100 s), is strongly dependent on particle size and environmental atmosphere, and results in irreversible decreases in emission intensity, large blue shifts of emission maximum, and increases in particle size distribution.