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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Theoretical studies of the modulation of polymer electronic and optical properties through the introduction of the electron-donating 3,4-ethylenedioxythiophene or electron-accepting pyridine and 1,3,4-oxadiazole moieties
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Theoretical studies of the modulation of polymer electronic and optical properties through the introduction of the electron-donating 3,4-ethylenedioxythiophene or electron-accepting pyridine and 1,3,4-oxadiazole moieties

机译：通过引入给电子3,4-亚乙基二氧噻吩或电子接受吡啶和1,3,4-恶二唑基团对聚合物电子和光学性质进行调节的理论研究

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One serious problem associated with polyfluorene and derivatives (PFs) as blue luminescent polymers is the significant energy barrier for hole or electron injections; thus they usually face charge injection and transport difficulties with the currently available cathode and anode materials. The incorporation of an electron-donating or -accepting unit is expected to improve the recombination of the charge carriers. In this paper, we apply quantum-chemical techniques to investigate three fluorene-based copolymers, copoly(2,5-ethylenedioxythiophene-alt-9,9'-dimethylfluorene) (PEF), copoly(2,5-pyridine-alt-9,9'-dimethylfluorene) (PPyF), and poly[(fluorene-2,7-diyl)-alt-(1,3,4-oxadiazole-2,5-diyl)] (PFO), in which Delta(H-L) [the energy difference between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), when n = infinity], the lowest excitation energies (E-g), ionization potentials (IP), electron affinities (EA), and lambda(abs) and lambda(em), are fine-tuned by the regular insertion of electron-donating unit 3,4-ethylenedioxythiophene (EDOT) or electronwithdrawing units pyridine and 1,3,4-oxadiazole. The results show that the alternate incorporation of electrondonating moiety EDOT increases the HOMO energy and thus reduces the IPs, and consequently the hole injection was greatly improved. On the other hand, even though both kinds of charge carriers will improve the electron-accepting ability, the results show that electron-withdrawing moieties greatly facilitate the electrontransporting. Especially in PFO, the highly planar structural character resulted from the strong push-pull effect between the fluorene ring and the 1,3,4-oxadiazole ring and a weak interaction between the nitrogen and oxygen atoms in 1,3,4-oxadiazole ring and the hydrogen atom of the fluorene ring, significantly lowering the LUMO energy levels and thus improve the electron-accepting and transporting properties by the low LUMO energy levels.
机译：与聚芴及其衍生物（PFs）作为蓝色发光聚合物有关的一个严重问题是空穴或电子注入的显着能量屏障。因此，它们通常在使用现有的阴极和阳极材料时面临电荷注入和传输困难。预期引入电子给体或电子接受单元将改善电荷载流子的重组。在本文中，我们应用量子化学技术研究了三种芴基共聚物，共聚（2,5-乙烯二氧噻吩-alt-9,9'-二甲基芴）（PEF），共聚（2,5-吡啶-alt-9 ，9'-二甲基芴）（PPyF）和聚[（芴-2,7-二基）-alt-（1,3,4-恶二唑-2,5-二基）]（PFO），其中Delta（HL ）[当n =无穷大时，最高占据分子轨道（HOMO）与最低未占据分子轨道（LUMO）之间的能量差]，最低激发能（Eg），电离势（IP），电子亲和力（EA），和lambda（abs）和lambda（em），可以通过定期插入供电子单元3,4-乙烯二氧噻吩（EDOT）或吸电子单元吡啶和1,3,4-恶二唑来进行微调。结果表明，交替结合电子给体部分EDOT增加了HOMO能量，从而降低了IP，因此大大改善了空穴注入。另一方面，即使两种电荷载流子都将提高电子接受能力，结果表明吸电子部分极大地促进了电子的传输。特别是在PFO中，芴环与1,3,4-恶二唑环之间的强推挽效应以及1,3,4-恶二唑环中的氮与氧原子之间的弱相互作用导致了高度平面的结构特征和芴环的氢原子显着降低了LUMO能级，因此通过低LUMO能级提高了电子接受和传输性能。

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