Enhancing Mechanical Deformability of Rigid Conjugated Polymers through Functional Additive-Induced Persistence Length Modulation

Abstract

Plastic electronics with deformable semiconducting polymer layers have emerged as a promising future technology. The design of semiconducting layers with tunable mechanical properties is crucial to improving the performance and reliability of plastic electronics, particularly for flexible and stretchable devices. Here, a method is demonstrated for systematically controlling the persistence length, allowing improvement of the mechanical properties of a single conjugated polymer system without the need for complex chemical modifications to the rigid backbone. The effects of plasticizing molecular additives (PMAs) on the rigidity of conjugated chains are thoroughly investigated through persistence length analysis. Solution-based small-angle neutron scattering reveals how different PMAs influence the persistence length of the benchmark rigid conjugated polymer PDPP2T-TT-OD. The mechanical, thermal, morphological, and electrical properties of PMA-blended films are evaluated under deformation. The results show that the mechanical modulus is primarily influenced by modification of the persistence length and the formation of uniformly entangled networks with smaller crystalline grains. The analysis suggests that the uniform distribution of PMAs in PDPP2T-TT-OD films, combined with physically crosslinked chains, significantly enhances thin film deformability. Notably, charge mobility remains stable even after stretching to 100% strain. These findings provide valuable insights into the design principles of PMA-blended conjugated polymer systems, offering a pathway for tailoring mechanical properties in future plastic electronics.