Tuning Solution-State Aggregation for Shearing-Induced Alignment and High Mobility Transport in Conjugated Polymers.

Abstract

Clarifying the evolution of solution-state aggregation of conjugated polymers into ordered thin films under external forces remains one of the key issues in developing high-performance polymer electronics. Here, a strategy is provided to tailor the polymer aggregation and their responsiveness to solution-shearing forces by tuning intermolecular interactions, aiming for efficient charge transport. Using a typical n-type conjugated polymer as the model system, we systematically modulate the balance between backbone-solvent and side chain-solvent interactions to design distinct aggregate structures. In the backbone-selective solvent of 1-chloronaphthalene, enhanced backbone solvation at elevated temperatures leads to loosely packed, rod-like aggregates that align efficiently under directional shear, yielding highly ordered films with electron mobilities up to 4.74 cm² V^-1 s^-1. In contrast, in the side-chain-selective solvent of trimethylbenzene, polymer chains form disordered network-like aggregates that resist alignment and produce less ordered films with mobilities of 2.20 cm² V^-1 s^-1. Additionally, similar enhancements in charge-transport mobility are also observed with two other representative polymers using the same strategy. This work establishes the critical role of intermolecular interaction-driven aggregate design in dictating shearing-induced structural evolution, offering a robust framework for the fabrication of high-mobility conjugated polymer films.