Hynynen Jonna, Kiefer David, Yu Liyang, Kroon Renee, Munir Rahim, Amassian Aram, Kemerink Martijn, Müller Christian
Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 41296 Göteborg, Sweden.
Division of Physical Sciences & Engineering and KAUST Solar Center (KSC), King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia.
Macromolecules. 2017 Oct 24;50(20):8140-8148. doi: 10.1021/acs.macromol.7b00968. Epub 2017 Oct 11.
Molecular p-doping of the conjugated polymer poly(3-hexylthiophene) (P3HT) with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) is a widely studied model system. Underlying structure-property relationships are poorly understood because processing and doping are often carried out simultaneously. Here, we exploit doping from the vapor phase, which allows us to disentangle the influence of processing and doping. Through this approach, we are able to establish how the electrical conductivity varies with regard to a series of predefined structural parameters. We demonstrate that improving the degree of solid-state order, which we control through the choice of processing solvent and regioregularity, strongly increases the electrical conductivity. As a result, we achieve a value of up to 12.7 S cm for P3HT:F4TCNQ. We determine the F4TCNQ anion concentration and find that the number of (bound + mobile) charge carriers of about 10 mol cm is not influenced by the degree of solid-state order. Thus, the observed increase in electrical conductivity by almost 2 orders of magnitude can be attributed to an increase in charge-carrier mobility to more than 10 cm V s. Surprisingly, in contrast to charge transport in undoped P3HT, we find that the molecular weight of the polymer does not strongly influence the electrical conductivity, which highlights the need for studies that elucidate structure-property relationships of strongly doped conjugated polymers.
用2,3,5,6-四氟-7,7,8,8-四氰基对苯二醌二甲烷（F4TCNQ）对共轭聚合物聚（3-己基噻吩）（P3HT）进行分子p型掺杂是一个被广泛研究的模型体系。由于加工和掺杂通常同时进行，其潜在的结构-性能关系尚未得到很好的理解。在这里，我们利用气相掺杂，这使我们能够区分加工和掺杂的影响。通过这种方法，我们能够确定电导率如何随一系列预定义的结构参数而变化。我们证明，通过选择加工溶剂和区域规整度来控制固态有序度的提高，会显著提高电导率。结果，我们得到了P3HT:F4TCNQ高达12.7 S/cm的值。我们测定了F4TCNQ阴离子浓度，发现约10^21 mol/cm³的（束缚+移动）电荷载流子数量不受固态有序度的影响。因此，观察到的电导率增加近2个数量级可归因于电荷载流子迁移率增加到超过10^-3 cm² V^-1 s^-1。令人惊讶的是，与未掺杂的P3HT中的电荷传输相反，我们发现聚合物的分子量对电导率没有强烈影响，这突出了阐明强掺杂共轭聚合物结构-性能关系的研究的必要性。
