Differentiation between Shallow and Deep Charge Trap States on Single Poly(3-hexylthiophene) Chains through Fluorescence Photon Statistics
Differentiation between Shallow and Deep Charge Trap States on Single Poly(3-hexylthiophene) Chains through Fluorescence Photon Statistics
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DOI：
10.1002/cphc.201500719
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发表时间：
2015-12-01
期刊：
影响因子：
2.9
通讯作者：
Vogelsang, Jan
中科院分区：
文献类型：
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作者：
Grussmayer, Kristin S.;Steiner, Florian;Vogelsang, Jan
单个共轭高聚物链发出的光致发光的闪烁是单分子光谱学的中心观测之一。可以通过评估动态猝灭来提取重要信息，例如关于激发能量转移的信息。然而，导致光致发光猝灭的陷阱态的性质通常仍然不清楚。我们详细研究了用扫描电子显微镜获得的单链聚(3-己基噻吩基)(P3HT)的光子统计。光子统计信息提供了单个链上独立发射区域的数量和亮度的度量。在眨眼的过程中，可以跟随这些可观测到的信息。发光强度的降低与1)发射点平均亮度的降低或2)发射区数目的减少相关。我们将这些现象归因于1)浅层电荷陷阱的形成，它可以同时弱地影响单链的所有发射区；以及2)深陷阱的形成，它对单链内的小区域有很强的影响。
Blinking of the photoluminescence (PL) emitted from individual conjugated polymer chains is one of the central observations made by single-molecule spectroscopy (SMS). Important information, for example regarding excitation energy transfer, can be extracted by evaluating dynamic quenching. However, the nature of trap states, which are responsible for PL quenching, often remains obscured. We present a detailed investigation of the photon statistics of single poly(3-hexylthiophene) (P3HT) chains obtained by SMS. The photon statistics provide a measure of the number and brightness of independently emitting areas on a single chain. These observables can be followed during blinking. A decrease in PL intensity is shown to be correlated with either 1) a decrease in the average brightness of the emitting sites; or 2) a decrease in the number of emitting regions. We attribute these phenomena to the formation of 1) shallow charge traps, which can weakly affect all emitting areas of a single chain at once; and 2) deep traps, which have a strong effect on small regions within the single chains.