Control of aggregate formation in poly(3-hexylthiophene) by solvent, molecular weight, and synthetic method
Control of aggregate formation in poly(3-hexylthiophene) by solvent, molecular weight, and synthetic method
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DOI：
10.1002/polb.23022
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发表时间：
2012-03-15
影响因子：
--
通讯作者：
Koehler, Anna
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文献类型：
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作者：
Scharsich, Christina;Lohwasser, Ruth H.;Koehler, Anna
聚（3-己基噻吩）中聚集体的形成取决于分子量、溶剂和合成方法。因此，这些参数的相互作用在很大程度上控制了设备的性能。为了定量了解这些因素如何控制P3HT的最终电子特性，我们测量了溶液和薄膜中的吸收以及晶体管中产生的场效应迁移率。通过对吸收光谱的详细分析，我们推断出形成的聚集体的比例，聚集体内的激子耦合和聚集体内的共轭长度，所有这些都是溶剂质量的函数，分子量从5到19 kDa。由此，我们推断出聚合链的结构。虽然5kda样品形成直链，但11kda和19kda链是扭结或折叠的，其共轭长度随着溶剂质量的降低而增加。即使溶剂质量较差，也能得到聚合链的最大分数（约55 +/- 5%）。我们证明了在溶液中诱导聚集导致薄膜中聚集性质的控制。正如预期的那样，场效应迁移率与聚集倾向相关。相应地，我们发现，对于低分子量样品（=11 kDa），需要一个定义明确的合成方法来定制窄分子量分布，以获得高达0.01 cm2/Vs的高场效应迁移率，而对于高分子量样品（如果通过提取去除低分子量组分），合成方法的影响可以忽略不计。(C) 2011 Wiley期刊公司高分子学报（B辑），2012
Aggregate formation in poly(3-hexylthiophene) depends on molecular weight, solvent, and synthetic method. The interplay of these parameters thus largely controls device performance. In order to obtain a quantitative understanding on how these factors control the resulting electronic properties of P3HT, we measured absorption in solution and in thin films as well as the resulting field effect mobility in transistors. By a detailed analysis of the absorption spectra, we deduce the fraction of aggregates formed, the excitonic coupling within the aggregates, and the conjugation length within the aggregates, all as a function of solvent quality for molecular weights from 5 to 19 kDa. From this, we infer in which structure the aggregated chains pack. Although the 5 kDa samples form straight chains, the 11 and 19 kDa chains are kinked or folded, with conjugation lengths that increase as the solvent quality reduces. There is a maximum fraction of aggregated chains (about 55 +/- 5%) that can be obtained, even for poor solvent quality. We show that inducing aggregation in solution leads to control of aggregate properties in thin films. As expected, the field-effect mobility correlates with the propensity to aggregation. Correspondingly, we find that a well-defined synthetic approach, tailored to give a narrow molecular weight distribution, is needed to obtain high field effect mobilities of up to 0.01 cm2/Vs for low molecular weight samples (=11 kDa), while the influence of synthetic method is negligible for samples of higher molecular weight, if low molecular weight fractions are removed by extraction. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012