Critical Role of Electron-donating Thiophene Group on the Thermomechanical Property of Donor-Acceptor Semiconducting Polymers

Organic semiconducting polymers are promising candidates for stretchable electronics for their mechanical compliance. Donor-Acceptor type conjugated polymers have been the key drive for recent boost in device performance. Up to date, the effect of the backbone structure on the thermomechanical property of conjugated polymers has not been carefully studied. This paper investigated the structure and thin film mechanical property relationship for donor-acceptor polymers with systematically varied backbone structures. The pseudo-free standing tensile test was used to obtain the full stress-strain curve, the glass transition temperature was measured for both thin and bulk films. In the meantime, detailed morphology was detected using AFM, UV-vis, and GIWAXS for further understanding. A general trend was observed and applied to the design of new stretchable conjugated polymers.