Mechanical, Thermal, and Electrical Properties of Flexible Polythiophene with Disiloxane Side Chains

Poly(3-hexylthiophene) (P3HT) is widely shown to have considerable advantages in photovoltaic cells, including excellent electrical performance, but its fragility remains a challenge for material applications and processing of stretchable devices. Herein, high-molecular-weight and highly regioregular poly(3-substituted thiophene) with disiloxane moieties in the side chains (P3SiT) is synthesized. An investigation of the molecular structure and physical properties of self-supported cast films of P3SiT reveals excellent flexible mechanical properties derived from the disiloxane groups in the side chains. The larger fracture strain reaches over 200% compared with that of poly(3-hexylthiophene) (14%). In addition, its Young's modulus (43 MPa) and low glass transition temperature (-10 degrees C) result in a typical elastic mechanical property. For the electrical property, the sheet resistivity of the drawn thiophene polymer shows the value almost equal to that of poly(3-hexylthiophene). The anisotropy of electrical resistivity is observed due to orientation of the drawn polymer.