Excited State Behavior of Single Strand and Bulk P3HT in Contact with a Au-Nanowire Array
Excited State Behavior of Single Strand and Bulk P3HT in Contact with a Au-Nanowire Array
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单链和块状 P3HT 与金纳米线阵列接触的激发态行为
DOI：
10.1021/acs.jpcc.7b12444
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Piotrowiak Piotr
中科院分区：
文献类型：
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作者：
Liu Mengdi;Hirata Shuzo;Iyoda Tomokazu;Vacha Martin;Piotrowiak Piotr
泵浦探针瞬态吸收和单分子荧光显微镜揭示了区域规则性 (RR) P3HT 与六角形金纳米线阵列相互作用的多方面激发态行为。在存在纳米线阵列的情况下，检测到单链 P3HT 的荧光强度平均增加 5 倍，其中最强的发射器的亮度超过玻璃上对应物的亮度 40 倍。单分子轨迹表明，相同的聚合物链能够表现出一系列增强水平。金基板上的“关闭”周期非常长且不稳定。这种行为归因于线和金属之间的零星电子转移事件。与玻璃载体相比，沉积在同一金纳米线阵列上的块状 P3HT 显示出单线态激子的产率和寿命显着降低，这表明金属的接近大大加速了激子解离和电荷复合。有趣的是，在金属存在的情况下观察到三重态激子数量的大幅增加，表明自旋-自旋相关性的损失要快得多。批量 P3HT 结果表明，在单分子实验中观察到的大荧光增强仅发生在少数发射器上，这些发射器被偶然放置在相对于金属的最佳距离和方向上。
Pump–probe transient absorption and single molecule fluorescence microscopy reveal multifaceted excited state behavior of regioregular (RR) P3HT interacting with a hexagonal array of Au nanowires. An average 5-fold increase of fluorescence intensity has been detected for single strands of P3HT in the presence of the nanowire array, with the strongest emitters exceeding the brightness of their counterparts on glass by a factor of 40. The single molecule trajectories show that the same polymer strand is capable of exhibiting a range of enhancement levels. The “off” periods on the Au substrate are exceptionally long and erratic. This behavior is attributed to sporadic electron transfer events between the strand and the metal. Bulk P3HT deposited on the same Au-nanowire array shows a dramatic reduction of the yield and lifetime of singlet excitons in comparison with the glass support, indicating that the proximity of the metal greatly accelerates both exciton dissociation and charge recombination. Interestingly, a large increase of the triplet exciton population is observed in the presence of the metal, indicating a much faster loss of the spin–spin correlation. The bulk P3HT results suggest that the large fluorescence enhancement observed in the single molecule experiments occurs only for a few emitters which have been fortuitously placed at the optimum distance and orientation with respect to the metal.