Dependence of regioregular poly(3-hexylthiophene) film morphology and field-effect mobility on molecular weight
Dependence of regioregular poly(3-hexylthiophene) film morphology and field-effect mobility on molecular weight
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DOI：
10.1021/ma047415f
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发表时间：
2005-04-19
期刊：
影响因子：
5.5
通讯作者：
Toney, MF
中科院分区：
文献类型：
--
作者：
Kline, RJ;McGehee, MD;Toney, MF
形态表征已被用来解释先前观察到的薄膜晶体管测量的载流子迁移率与共轭聚合物区域的数平均分子量(MW)之间的强烈相关性。原子力显微镜和X射线衍射分析表明，低迁移率、低分子量薄膜具有高度有序的纳米棒结构，而高迁移率、高分子量薄膜具有较少的有序、各向同性的结节结构。通过改变浇注条件或对样品进行热处理来改变薄膜的形貌，对低迁移率、低分子量薄膜的电荷输运和形貌有很大的影响，但对高分子量薄膜的影响不大。平面掠入射X射线散射表明，当迁移率一定时，面内pi堆积峰随迁移率的增加而增加。当Mw改变时，这种相关性被打破，证实行星内堆积不会导致迁移率-Mw关系。我们认为，无序的磁区边界和链长对电子结构的内在影响共同导致了迁移率-MW关系。
Morphological characterization has been used to explain the previously observed strong correlation between charge carrier mobility measured with thin-film transistors and the number-average molecular weight (MW) of the conjugated polymer regioregular poly(3-hexylthiophene). Atomic force microscopy and X-ray diffraction show that the low-mobility, low-MW films have a highly ordered structure composed of nanorods and the high-mobility, high-MW films have a less ordered, isotropic nodule structure. Modifying the morphology for a constant MW by changing the casting conditions or annealing the samples strongly affects the charge transport and morphology in the low-mobility, low-MW films, but has little effect on the high-MW films. In-plane grazing incidence X-ray scattering shows the in-plane pi-stacking peak increases when the mobility increases for a constant MW. When the MW is changed, this correlation breaks down, confirming that in-planet-stacking does not cause the mobility-MW relationship. We believe a combination of disordered domain boundaries and inherent effects of chain length on the electronic structure cause the mobility-MW relationship.