Impact of Isomeric Structures on Transistor Performances in Naphthodithiophene Semiconducting Polymers
Impact of Isomeric Structures on Transistor Performances in Naphthodithiophene Semiconducting Polymers
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DOI：
10.1021/ja201591a
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发表时间：
2011-05-04
影响因子：
15
通讯作者：
Takimiya, Kazuo
中科院分区：
文献类型：
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作者：
Osaka, Itaru;Abe, Toru;Takimiya, Kazuo
在聚噻吩半导体骨架中引入了四种线型和角型异构体萘二噻吩（NDT），并对其场效应晶体管性能进行了表征。含萘并[1，2-B：5，6-b ']二噻吩（NDT 3）的聚合物（一种角形NDT）在四种NDT基聚合物中表现出最高的迁移率，接近0.8 cm（2）V（-1）s（-1），这是迄今为止报道的半导体聚合物中最高的。有趣的是，NDT基聚合物的迁移率趋势与我们的预期相反;具有角形NDT的聚合物显示出比具有线性NDT的聚合物更高的迁移率，尽管事实上萘并[2，3-B：6，7-b ']二噻吩（NDT 1），一种线性NDT，在小分子体系中显示出最高的迁移率。X-射线衍射研究表明，角形NDT基聚合物具有高度有序的结构，具有非常接近的3.6埃的π堆积距离，而线性NDT基聚合物具有非常弱或没有π堆积顺序，这与迁移率的趋势非常一致。这种有序结构的性质可以通过考虑它们的分子形状来很好地理解。事实上，线性NDT（NDT 1）提供有角度的骨架，而有角度的NDT（NDT 3）提供伪直骨架，后者可以包装成高度有序的结构，从而促进电荷载流子传输。除了有序结构，电子结构似乎与载流子输运性质相关。MO计算，电离势的测量支持，建议，虽然HOMO是相对本地化的NDT核心内的线性NDT为基础的聚合物，这些显然是离域沿着的骨干角NDT为基础的聚合物。后者应促进有效的HOMO重叠之间的聚合物主链，是电荷载流子传输的主要路径，这也同意的迁移率的趋势。根据这些结果，我们得出结论，角度NDTs，特别是NDT 3，是有前途的高性能半导体聚合物的核心。因此，我们建议，分子的形状和电子结构是设计高性能半导体聚合物时要考虑的重要因素。
Four isomeric naphthodithiophenes (NDTs) with linear and angular shapes were introduced into the polythiophene semiconductor backbones, and their field-effect transistor performances were characterized. The polymers bearing naphtho[1,2-b:5,6-b']dithiophene (NDT3), an angular-shaped NDT, exhibited the highest mobilities of similar to 0.8 cm(2) V(-1)s(-1) among the four NDT-based polymers, which is among the highest reported so far for semiconducting polymers. Interestingly, the trend of the mobility in the NDT-based polymers was contrary to our expectations; the polymers with angular NDTs showed higher mobilities than those with linear NDTs despite the fact that naphtho[2,3-b:6,7-b']dithiophene (NDT1), a linear-shaped NDT, has shown the highest mobility in small-molecule systems. X-ray diffraction studies revealed that angular-NDT-based polymers gave the highly ordered structures with a very close pi-stacking distance of 3.6 angstrom, whereas linear-NDT-based polymers had a very weak or no pi-stacking order, which is quite consistent with the trend of the mobility. The nature of such ordering structures can be well understood by considering their molecular shapes. In fact, a linear NDT (NDT1) provides angular backbones and an angular NDT (NDT3) provides a pseudostraight backbone, the latter of which can pack into the highly ordered structure and thus facilitate the charge carrier transport. In addition to the ordering structure, the electronic structures seem to correlate with the carrier transport property. MO calculations, supported by the measurement of ionization potentials, suggested that, while the HOMOs are relatively localized within the NDT cores in the linear-NDT-based polymers, those are apparently delocalized along the backbone in the angular-NDT-based polymers. The latter should promote the efficient HOMO overlaps between the polymer backbones that are the main paths of the charge carrier transport, which also agrees with the trend of the mobility. With these results, we conclude that angular NDTs, in particular NDT3, are promising cores for high-performance semiconducting polymers. We thus propose that both the molecular shapes and the electronic structures are important factors to be considered when designing high performance semiconducting polymers.