Controllable Conformation Transfer of Conjugated Polymer toward High Photoelectrical Performance: The Role of Solvent in Induced-Crystallization Route

In the present work, polyimides with different conformation (dendritic, spherulitic, and laminar) were synthesized in different solvents. The strong solvent-dependent conformation variation is found intimately related to the specific interactions between the polymer chain and solvent molecules that have a primary driving force for the chain diffusion and rearrangement. Moreover, the photoelectrical properties of polyimide were sensitively influenced by the crystal structure and polymer morphology. In laminar conformation with strong intermolecular π–π interactions, the light absorption as well as the mobility and separation of photoinduced carriers were greatly improved compared with similar values of dendritic and spherulitic ones. For photocatalytic hydrogen evolution from water splitting, polyimide with laminar conformation exhibits 16 times enhancement in activity than the dendritic. This work provides further insight into the intrinsic interacting mechanism of solvent-induced crystallization of conjugated polymer and paves an innovative way for synthesis of efficient polymer semiconductor photocatalysts.