Bridges Colin R, Ford Michael J, Bazan Guillermo C, Segalman Rachel A
Department of Chemical Engineering and Materials, ‡Mitsubishi Centre for Advanced Materials, and §Centre for Polymers and Organic Solids, Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States.
Department of Chemical Engineering and Materials, Mitsubishi Centre for Advanced Materials, and §Centre for Polymers and Organic Solids, Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States.
ACS Macro Lett. 2017 Jun 20;6(6):619-624. doi: 10.1021/acsmacrolett.7b00273. Epub 2017 May 25.
Intermolecular interactions in conjugated polymers influence crystallinity, self-assembly, and packing motif, factors which in turn crucially impact charge transport properties such as carrier mobility in organic electronic devices. Correlated alignment of molecular and crystalline morphologies provides direct pathways for charge carriers to follow; however, the role of intermolecular interactions in achieving this is unexplored. Herein, we synthesize a series of lyotropic liquid crystalline conjugated polymers with variable side-chain structure to lend distinct steric repulsion and van der Waals attractive forces to each mesophase. We use this to investigate the role of intermolecular interactions on mesophase alignment. The strength of intermolecular interaction for each mesophase is compared by measuring melting temperature, π-stacking distance, and the Maier-Saupe interaction parameter. In general we find that side-chain structure can impact interaction strength by varying steric repulsion and backbone attractions and that the Maier-Saupe interaction parameters correlate with higher degrees of alignment after shearing, achieving a dichroic absorbance ratio of up to 2. This observation is used to develop equilibrium processing methods for fabricating macroscopically aligned polymer substrates used in transistors, improving mobility by a factor of 3 compared to spin-coated devices.
共轭聚合物中的分子间相互作用会影响结晶度、自组装和堆积模式，而这些因素又会对电荷传输特性产生至关重要的影响，例如有机电子器件中的载流子迁移率。分子形态与晶体形态的相关排列为电荷载流子提供了直接的传输路径；然而，分子间相互作用在实现这一点上所起的作用尚未得到探索。在此，我们合成了一系列具有可变侧链结构的溶致液晶共轭聚合物，以便为每个中间相赋予不同的空间排斥力和范德华吸引力。我们以此来研究分子间相互作用对中间相对列的作用。通过测量熔点、π堆积距离和迈尔 - 绍佩相互作用参数，比较了每个中间相的分子间相互作用强度。总体而言，我们发现侧链结构可以通过改变空间排斥力和主链吸引力来影响相互作用强度，并且迈尔 - 绍佩相互作用参数与剪切后更高程度的排列相关，实现了高达2的二向色性吸光度比。这一观察结果被用于开发平衡加工方法，以制造用于晶体管的宏观排列聚合物基板，与旋涂器件相比，迁移率提高了3倍。
