Pyrazine as a noncovalent conformational lock in semiconducting polymers for enhanced charge transport and stability in thin film transistors†
Backbone engineering was performed on highly rigid semiconducting polymers to include diketopyrropyrrole (DPP) units combined with pyrazine-containing moieties. These new moieties were shown to improve backbone planarity through a conformational locking effect between nitrogen and sulfur atoms. The new polymers, characterized by various techniques, were shown to possess a highly crystalline and smooth solid-state morphology, optimal for charge transport. To verify the potential of the new semiconductor for organic electronics, a series of organic field-effect transistors was fabricated. Interestingly, the new polymer was shown to possess a charge mobility of 0.27 cm2 V−1 s−1 and on/off current ratio of 107, which is an improvement when compared to a thiophene analogue. More importantly, the polymer led to devices with high stability, with a retention of device characteristics when exposed to the same bias stress comparable to a benchmark reference polymer. The utilization of pyrazine-containing moieties as a conformational lock is a promising strategy to achieve a high performance conjugated polymer in a simple manner. Moreover, their utilization in bottom-gate bottom-contact devices highlights the potential of this new semiconductor for fully printed high-performance electronics.