The preparation of supramolecular mesoscale structures with high intrinsic order and orientation based on π-conjugated systems is of fundamental interest for studying their photophysical characteristics as well as for potential applications in (nano)photonics. However, the preparation, isolation and transfer of individual structures to substrates without compromising their structural integrity is challenging. Here we report on the controlled formation of hierarchical superstructures based on poly(3-hexylthiophene) (P3HT) comprising highly ordered and oriented P3HT nanofibers with lengths of up to 20 μm via a two-step self-assembly process. In the first step, we prepare defined supramolecular ribbons of N,N′-1,4-phenylenebis[4-pyridinecarboxamide]. In the second step, these ribbons act as efficient nucleation sites for the transcrystallization of P3HT into μm-long nanofibers from solution. The resulting shish-kebab-like superstructures can be purified and deposited on substrates without compromising their structural integrity. The densely packed and well-arranged P3HT nanofibers within the isolated superstructures feature a high orientational order parameter close to one up to a distance of 15 μm away from the initial nucleation sites. A systematic variation of photoluminescence spectra along the P3HT nanofibers in isolated superstructures indicates an increasing defect density toward the nanofiber end due to fractionation during growth. We anticipate that these findings can be transferred to designing and realizing superstructures as components for nanophotonic devices or light-harvesting antennae.

中文翻译：

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具有高度取向 P3HT 纳米纤维的孤立分层超结构


基于π共轭体系制备具有高本征有序和取向的超分子介尺度结构对于研究其光物理特性以及在（纳米）光子学中的潜在应用具有重要意义。然而，在不影响其结构完整性的情况下，将单个结构制备、分离和转移到基材上是具有挑战性的。在这里，我们报告了基于聚（3-己基噻吩）（P3HT）的分层超结构的受控形成，该超结构由高度有序和定向的 P3HT 纳米纤维组成，长度可达 20 μm，通过两步自组装工艺。在第一步中，我们制备了 N，N'-1,4-苯基二 [4-吡啶甲酰胺] 的确定的超分子条带。在第二步中，这些条带充当 P3HT 从溶液中转结晶成 μm 长纳米纤维的有效成核位点。所得的 shish-kebab 状上层结构可以被纯化并沉积在基材上，而不会影响其结构完整性。孤立的超结构内密集堆积和排列良好的 P3HT 纳米纤维具有接近 1 的高取向顺序参数，距离初始成核位点最远可达 15 μm。在孤立的超结构中，沿 P3HT 纳米纤维的光致发光光谱的系统变化表明，由于生长过程中的分馏，朝向纳米纤维末端的缺陷密度增加。我们预计这些发现可以转移到设计和实现作为纳米光子器件或光收集天线组件的超结构。