Highly luminescent polymer single crystals with anisotropic optical and electronic properties from appropriately designed, defect-free regioregular polythiophenes

薄膜形态与有机电子器件光电性能的相关性经常在文献中报道。然而，多个参数的干扰通常是普遍存在的。因此，精确的结构-功能关系和单个参数的影响的识别仍然是难以捉摸的，因此，特别是半结晶共轭聚合物的光电性质的解释是复杂的，由于存在许多可能的形态组成的结晶和无定形域。聚合物的结晶导致各种有序度的层状晶体。在这里，我们的目标是减少结构特征的复杂性，基于我们的研究，从无缺陷，窄分布和regioregular聚噻吩的聚合物单晶。在这样的单晶中，链在所有相关的长度尺度上都是有序的。 本论文的主要研究内容包括：1.通过Kumada催化剂转移缩聚反应（KCTP）及其外部引发方式，合成无缺陷的聚二烷基苯基噻吩（PDAPT）。为此，我们将合成并引入具有半不稳定的混合P，N配体的镍络合物，以将迄今已知的良好聚合性能转移到具有空间位阻侧链的单体。PDAPT的选择在于其特殊的晶体结构：由于独特的侧链模式，不可能有π-π相互作用，这与聚噻吩中通常观察到的π-π-堆叠形成对比，例如P3 HT。无缺陷的P3 HT和无缺陷的PDAPT将采用自引晶结晶成单晶。实验和分子参数的影响，如时间，温度，浓度，分子量，多分散性，侧链的长度，和π-π相互作用的大小，形状和完整性的所得单晶将阐明。3.各向异性的光电性能的所有单晶将被调查作为一个功能的晶体方向。这需要吸收，光致发光，电荷载流子迁移率和激子扩散长度，这将系统地确定为一系列P3 HT（π-π堆叠）和PDAPT（没有π-π堆叠可能）聚合物的分子量和侧链不同的晶胞方向的函数。一个关键点是π-π相互作用对电荷传输的影响。这将通过比较PDAPT与P3 HT来解决。

Correlations of thin film morphology with the resulting opto-electronic properties of organic electronic devices are often reported in the literature. However, the interference of several parameters is generally prevalent. Hence, precise structure-function relationships and the identification of the influence of individual parameters have remained elusive, and therefore the interpretation of opto-electronic properties of especially semi-crystalline conjugated polymers is complicated due to the presence of a multitude of possible morphologies consisting of crystalline and amorphous domains. Crystallization of polymers leads to lamellar crystals of various degrees of order. Here, we aim at reducing the complexity of structural features by basing our studies on polymeric single crystals made from defect-free, narrow distributed and regioregular polythiophenes. In such single crystals, the chains are ordered across all relevant length-scales. The main aims of this interdisciplinary projekt between polymer chemistry and experimental physics can be summarized as follows:1.The synthesis of defect-free poly(dialkylphenylthiophene) (PDAPT), which entails the controlled Kumada Catalyst Transfer Polycondensation (KCTP) of sterically hindered monomers as well as its variant of external initiation. To this end we will synthesize and introduce nickel complexes with hemilabile, mixed P,N ligands to transfer the good polymerization performance known so far to monomers with sterically hindered side chains. The choice of PDAPT lies in its special crystal structure: No pi-pi interactions are possible because of the unique side-chain pattern, which is in contrast to the generally observed pi-pi-stacking in polythiophenes, e.g. P3HT.2. Defect-free P3HT and defect-free PDAPT will be crystallized into single crystals employing self-seeding. The influence of experimental and molecular parameters such as time, temperature, concentration, molecular weight, polydispersity, side chain length, and pi-pi-interactions on the size, shape and perfection of the resulting single crystals will be elucidated.3.The anisotropic optoelectronic properties of all single crystals will be investigated as a function of the crystal direction. This entails absorption, photoluminescence, charge carrier mobility and exciton diffusion lengths, which will be systematically determined as a function of unit cell direction for a series of P3HT (pi-pi stacking) and PDAPT (no pi-pi stacking possible) polymers differing in molecular weight and side chain. One crucial point will be the influence of pi-pi interactions on charge transport. This will be resolved by comparing PDAPT with P3HT.