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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Photoinduced electron transfer and nonlinear absorption in poly(carbazole-alt-2,7-fluorene)s bearing perylene diimides as pendant acceptors
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Photoinduced electron transfer and nonlinear absorption in poly(carbazole-alt-2,7-fluorene)s bearing perylene diimides as pendant acceptors

机译：以per二酰亚胺为侧基受体的聚咔唑-alt-2,7-芴中的光诱导电子转移和非线性吸收

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This paper reports the synthesis, photophysical behavior, and use in nanosecond optical-pulse suppression of a poly(2,7-carbazole-alt-2,7-fluorene) and a poly(3,6-carbazole-alt-2,7-fluorene) in which the carbazole N-positions are linked by an alkyl chain to one of the nitrogen atoms of a perylene-3,4,9,10-tetracarboxylic diimide (PDI) acceptor. It was found that the PDI pendants on the polymer side chain aggregated even in dilute solution, which extended the onset of PDI absorption into the near-infrared (NIR). Transient-absorption spectra of these polymers provide evidence for efficient electron transfer following either donor or acceptor photoexcitation to form long-lived charge-separated species, which exhibit strong absorption in the NIR. The spectral overlap between the transient species and the long-wavelength absorption edge of the aggregated PDI leads to reverse saturable absorption at 680 nm that can be used for optical-pulse suppression. Additionally, at high input energies, two-photon absorption mechanisms may also contribute to the suppression. PDI-grafted polymers exhibit enhanced optical-pulse suppression compared with blends of model materials composed of unfunctionalized poly(carbazole-alt-2,7-fluorene)s and PDI small molecules.
机译：本文报道了聚（2,7-咔唑-alt-2,7-芴）和聚（3,6-咔唑-alt-2,7）的合成，光物理行为及其在纳秒光脉冲抑制中的应用。 -芴），其中咔唑N-位通过烷基链连接到a 3,4,9,10-四羧酸二酰亚胺（PDI）受体的氮原子之一上。发现即使在稀溶液中，聚合物侧链上的PDI侧基也会聚集，这将PDI吸收的开始扩展到了近红外（NIR）中。这些聚合物的瞬态吸收光谱为供体或受体光激发后形成长寿命的电荷分离物质（在NIR中显示出强吸收性）之后的有效电子转移提供了证据。瞬态物质与聚集的PDI的长波长吸收边缘之间的光谱重叠会导致在680 nm处出现反向饱和吸收，可用于光脉冲抑制。另外，在高输入能量下，双光子吸收机制也可能有助于抑制。与由未官能化的聚咔唑-alt-2,7-芴和PDI小分子组成的模型材料的共混物相比，PDI接枝的聚合物显示出增强的光脉冲抑制能力。

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