Optimal Ambipolar Charge Transport of Thienylenevinylene-Based Polymer Semiconductors by Changes in Conformation for High-Performance Organic Thin Film Transistors and Inverters

We report the synthesis and characterization of thienylenevinylene-based donor–acceptor alternating copolymers (PTVPhI-Eh and PTVPhI-C12) as highly efficient ambipolar semiconductors in a thin film transistor. These polymers exhibit significantly improved hole and electron mobilities after thermal annealing. To determine the relationship between ambipolar charge transport and thermal annealing, we investigated these polymers using various analyses such as optical spectroscopy, Raman spectroscopy, computational quantum chemical calculation, X-ray diffraction, atomic force microscopy, and ambipolar charge mobility measurements. In pristine films, the polymer chains exhibited weak intra- and interchain ordering. However, when samples were annealed at sufficiently high temperatures, they exhibited a more ordered intra- and interchain conformation. As a result, we found a strong relationship between intra- and interchain conformational changes of the polymers and corresponding ambipolar charge transport properties during thermal annealing processes. Finally, we demonstrate complementary-like ambipolar inverters using a PTVPhI-Eh polymer. The largely shifted inverting voltage was improved for the thermally annealed inverters, which exhibited large voltage gains (∼40).