Design Principles for Enhancing Both Carrier Mobility and Stretchability in Polymer Semiconductors via Lewis Acid Doping.

With the rise of skin-like electronics, devices are increasingly coming into close contact with the human body, creating a demand for polymer semiconductors (PSCs) that combine stretchability with reliable electrical performance. However, balancing mechanical robustness with high carrier mobility remains a challenge. To address this, tris(pentafluorophenyl)borane (BCF) for Lewis acid doping is proposed to improve charge mobility while enhancing stretchability by increasing structural disorder. Through systematic investigation, several key structural principles have been identified to maximize the effectiveness of BCF doping in stretchable PSCs. Notably, increasing the lamellar stacking distance and reducing crystallinity facilitate the incorporation of BCF into the alkyl side-chain regions, thereby enhancing both mobility and stretchability. Conversely, stronger Lewis base groups in the main chain negatively impact these improvements. These results demonstrate that with a small addition of BCF, a two-fold increase in carrier mobility is achieved while simultaneously enhancing the crack onset strain to 100%. Furthermore, doped PSCs exhibit stable mobility retention under repeated 30% strains over 1000 cycles. This method of decoupling carrier mobility from mechanical properties opens up new avenues in the search for high-mobility stretchable PSCs.