Molecular weight optimization for intrinsically stretchable conjugated polymers: from film microstructure to strain-insensitive performance

Abstract

Intrinsically stretchable conjugated polymers show great potentials in wearable electronics owing to their good strain-tolerant optoelectrical performance under mechanical deformation. Molecular weight is a pivotal parameter for conjugated polymers that can largely affect film microstructure and mechanical/electrical performance. This review delves into the molecular weight optimization to develop strain-insensitive intrinsically stretchable conjugated polymer films from the view of morphology control and strain dissipation. We first introduce how the microstructure of conjugated polymer films evolves with molecular weight in terms of solution aggregation, chain entanglement and phase separation. Next, we discuss the impact of molecular weight on the electrical performance of conjugated polymer films by analyzing the intrachain and interchain charge transport behaviors. Third, we summarize recent studies on the strain energy dissipation mechanisms of conjugated polymer films with different molecular weight and their correlations with charge transport. Finally, we present the conclusions and perspectives in molecular weight control for developing mechanically-reliable stretchable conjugated polymer films.