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首页> 外文期刊>The journal of physical chemistry, B. Condensed matter, materials, surfaces, interfaces & biophysical >Exciton Migration by Ultrafast Forster Transfer in Highly Doped Matrixes
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Exciton Migration by Ultrafast Forster Transfer in Highly Doped Matrixes

机译：高掺杂基质中超快Forster转移的激子迁移

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摘要

The energy transfer between dye molecules and the mobility of the corresponding excitons are investigated in polymethyl methacrylate films highly doped with perylene bisimide dyes.The dynamics is measured by group delay corrected,femtosecond broad-band spectroscopy revealing the transfer route via absorption changes that are specific for the participating species.In films doped with 0.14 M perylene orange an ultrafast homotransfer between the dye molecules is found by analyzing the loss of the excitation-induced anisotropy.The process exhibits a stretched exponential time dependence which is characteristic for Forster energy transfer between immobilized molecules.The transfer time is 1.5 ps for an average transfer distance of 2.3 nm and results in a high mobility of the optically generated excitons.In addition,we find that the excitons move to perylene orange dimers,which have formed in low concentration during the sample preparation.The observed energy transfer time is slightly shorter than expected for a direct Forster transfer and indicates that exciton migration by multistep transfer between the monomers speeds up the transport to the dimers.In samples doped with perylene orange and perylene red heterotransfer to perylene red takes place with transfer times down to 600 fs.The mechanism is Forster transfer as demonstrated by the agreement with calculations assuming electric dipole interaction between immobilized and statistically distributed donor and acceptor units.The model predicts the correct time dependence and concentration scaling for highly doped as well as diluted samples.The results show that ultrafast exciton migration between dye molecules in highly doped matrixes is an attractive and efficient mechanism to transport and collect energy in molecular systems and organic electronic devices.Further optimization should lead to a loss-free transport over distances typical for the thickness of active layers in these systems.
机译：在高浓度per二酰亚胺染料掺杂的聚甲基丙烯酸甲酯薄膜中研究了染料分子之间的能量转移和相应激子的迁移率。通过基团延迟校正，飞秒宽带光谱法测量了动力学，通过特定的吸收变化揭示了转移途径在掺杂有0.14 M ylene橙的薄膜中，通过分析激发引起的各向异性的损失，发现了染料分子之间的超快速均相转移。该过程表现出延长的指数时间依赖性，这是固定化之间Forster能量转移的特征分子的转移时间为1.5 ps，平均转移距离为2.3 nm，导致光学产生的激子具有很高的迁移率。此外，我们发现激子向orange橙二聚体移动，per橙二聚体在低浓度时形成。样品制备。观察到的能量转移时间略短r比直接进行Forster转移的预期要好，这表明通过单体之间的多步转移进行的激子迁移加快了向二聚体的转移。在掺有per橙和per红的样品中，杂化转移至red红时的转移时间低至600 fs。该机制为Forster转移，如通过计算所假设的那样，并假定了固定和统计分布的供体和受体单元之间的电偶极相互作用，该模型预测了高掺杂和稀释样品的正确时间依赖性和浓度标度，结果表明超快高掺杂基质中染料分子之间的激子迁移是吸引和有效地在分子系统和有机电子设备中传输和收集能量的机制，进一步的优化应导致这些系统中有源层厚度的典型距离上的无损传输。

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