One-Dimensional Exciton Diffusion in Perylene Bisimide Aggregates
One-Dimensional Exciton Diffusion in Perylene Bisimide Aggregates
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DOI：
10.1021/jp107407p
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发表时间：
2011-02-10
影响因子：
2.9
通讯作者：
Lochbrunner, Stefan
中科院分区：
文献类型：
--
作者：
Marciniak, Henning;Li, Xue-Qing;Lochbrunner, Stefan
利用瞬态吸收光谱技术研究了苝酰亚胺J聚集体中激子的动力学和迁移率，时间分辨率为50 fs。瞬态光谱是兼容的激子离域长度的两个单体，并表明振动和构型弛豫过程是不相关的聚集体的光谱性质。增加泵浦脉冲能量和以这种方式增加初始激子密度导致加速的信号衰减和显著的激子激子湮灭动力学。通过假设扩散激子运动对数据进行建模，揭示了激子不能在空间的所有三个方向上自由迁移，但它们的迁移率被限制在一维。所观察到的各向异性支持这一观点，并指出反对直接福斯特转移介导的湮灭激子之间。从拟合过程中推导出扩散常数为1.29 nm（2）/ps，对应于测得的激子寿命为3.6 ns的最大激子扩散长度为96 nm。研究结果表明，J-聚集体的苝双酰亚胺是有前途的积木，以促进定向能量传输的光电有机器件或人工光捕获系统。
The dynamics and mobility of excitons in J-aggregates of perylene bisimides are investigated by transient absorption spectroscopy with a time resolution of 50 fs. The transient spectra are compatible with an exciton delocalization length of two monomers and indicate that vibrational and configurational relaxation processes are not relevant for the spectroscopic properties of the aggregates. Increasing the pump pulse energy and in that way the initial exciton density results in an accelerated signal decay and pronounced exciton exciton annihilation dynamics.. Modeling the data by assuming a diffusive exciton motion reveals that the excitons cannot migrate freely in all three directions of space but their mobility is restricted to one dimension. The observed anisotropy supports this picture and points against direct Forster-transfer-mediated annihilation between the excitons. A diffusion constant of 1.29 nm(2)/ps is deduced from the fitting procedure that corresponds to a maximal exciton diffusion length of 96 nm for the measured exciton lifetime of 3.6 ns. The findings indicate that J-aggregates of perylene bisimides are promising building blocks to facilitate directed energy transport in optoelectronic organic devices or artificial light-harvesting systems.