Strain-induced morphology evolution and charge transport in conjugated polymer films

Stretchable conjugated polymer films are pivotal in flexible and wearable electronics. Despite significant advancements in film stretchability through molecular engineering and multicomponent blending, these conjugated polymer films often exhibit limited elastic ranges and reduced carrier mobilities under large strain or after cyclic stretching. These limitations hinder their application in wearable electronics. Therefore, it is imperative to reveal the mechanical fatigue mechanisms and incorporate multiple strain energy dissipation strategies to enhance elastic deformation and electrical performance of stretched conjugated polymer films. In this review, we begin by introducing the typical mechanical behaviors of conjugated polymer films. Subsequently, we discuss the multiscale structural evolution under various stretching conditions based on both in-situ and ex-situ characterizations. This analysis is further related to the diverse strain energy dissipation mechanisms. We next establish the correlation between strain-induced microstructure and the electrical performance of stretched conjugated polymer films. After that, we propose to develop highly elastic conjugated polymer films by constructing stable crosslinks and promoting polymer dynamics in low-crystalline polymer films. Finally, we highlight the future opportunities for high-performance and mechanically stable devices based on stretchable conjugated polymer films.