Visualizing the multi-level assembly structures of conjugated molecular systems with chain-length dependent behavior

• Published in: Nature communications Vol. 14; no. 1; p. 3340
• Main Authors: Zhou, Yang-Yang, Xu, Yu-Chun, Yao, Ze-Fan, Li, Jia-Ye, Pan, Chen-Kai, Lu, Yang, Yang, Chi-Yuan, Ding, Li, Xiao, Bu-Fan, Wang, Xin-Yi, Shao, Yu, Zhang, Wen-Bin, Wang, Jie-Yu, Wang, Huan, Pei, Jian
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 07-06-2023; Nature Publishing Group; Nature Portfolio
• Subjects: 147/143; 639/166/898; 639/301/923/1028; 639/638/455/954; Aggregates; Assembly; Evolution; Fabrication; Humanities and Social Sciences; Microstructure; Molecular chains; Molecular conformation; Morphology; multidisciplinary; Network formation; Optimization; Optoelectronic devices; Polymers; Science; Science (multidisciplinary); Solid state
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-023-39133-w

It remains challenging to understand the structural evolution of conjugated polymers from single chains to solvated aggregates and film microstructures, although it underpins the performance of optoelectrical devices fabricated via the mainstream solution processing method. With several ensemble visual measurements, here we unravel the morphological evolution process of a model system of isoindigo-based conjugated molecules, including the hidden molecular assembly pathways, the mesoscale network formation, and their unorthodox chain dependence. Short chains show rigid chain conformations forming discrete aggregates in solution, which further grow to form a highly ordered film that exhibits poor electrical performance. In contrast, long chains exhibit flexible chain conformations, creating interlinked aggregates networks in solution, which are directly imprinted into films, forming interconnective solid-state microstructure with excellent electrical performance. Visualizing multi-level assembly structures of conjugated molecules provides a deep understanding of the inheritance of assemblies from solution to solid-state, accelerating the optimization of device fabrication.
A deep understanding of multi-level assembly structures of conjugated polymers is crucial for developing high performance conjugated polymers and optoelectronic devices, however, it remains a challenge. Here, the authors report the morphological evolution of multi-level assembly of a model system of isoindigo-based conjugated polymer.