Ordered Solid‐State Microstructures of Conjugated Polymers Arising from Solution‐State Aggregation

Controlling the solution‐state aggregation of conjugated polymers for producing specific microstructures remains challenging. Herein, a practical approach is developed to finely tune the solid‐state microstructures through temperature‐controlled solution‐state aggregation and polymer crystallization. High temperature generates significant conformation fluctuation of conjugated backbones in solution, which facilitates the polymer crystallization from solvated aggregates to orderly packed structures. The polymer films deposited at high temperatures exhibit less structural disorders and higher electron mobilities (up to two orders of magnitude) in field‐effect transistors, compared to those deposited at low temperatures. This work provides an effective strategy to tune the solution‐state aggregation to reveal the relationship between solution‐state aggregation and solid‐state microstructures of conjugated polymers. Using temperature‐controlled polymer aggregation, the solid‐state microstructures of conjugated polymers are finely tuned. The temperature‐controlled strategy enhances the molecular ordering in thin films and leads to efficient charge transport. A polymer transistor with tuned molecular ordering exhibited improved electron mobilities of up to 3.71 cm2 V−1 s−1, which is two orders of magnitude higher than the disordered samples.