Investigation of the Mobility–Stretchability Properties of Naphthalenediimide-Based Conjugated Random Terpolymers with a Functionalized Conjugation Break Spacer

To date, few studies of the mobility–stretchability properties of N-type semiconductors, including naphthalenediimide (NDI)-based polymers, have been conducted, and the preparation of intrinsically stretchable N-type semiconducting polymers is very important in the construction of stretchable electronics. In this study, three NDI-based random terpolymers are synthesized by introducing functionalized conjugation break spacers (CBSs) with ester, sulfone, and amide groups. N-type semiconducting polymers with ester and amide-based CBSs undergo conformational reorganization during stretching, as evidenced by the progressive evolution of mixed edge-on and face-on orientations, as well as the increased UV–vis dichroic ratio. This phenomenon is attributed to the improved chain conformability and ductility from the randomized distribution of the CBSs along the polymer backbone with more planar CBSs. Therefore, polymers with ester-based CBSs achieve superior orthogonal electron mobility (μ_e) >0.005 cm² V^–1 s^–1 and an average μ_e retention of 61% after 400 cyclic stretching at 60% strain. To the best of our knowledge, this study is the first to decipher the mobility–stretchability properties of N-type semiconducting polymers that warrant further investigation for constructing intrinsically stretchable and wearable electronics.