Synergistic Effect of Regioregular and Regiorandom Poly(3‐hexylthiophene) Blends for High Performance Flexible Organic Field Effect Transistors

Abstract

Decreased conjugated polymer regioregularity can provide for mechanical flexibility, which is favorable for the fabrication of flexible electronics; however, concomitant decreased thin‐film crystallinity severely deteriorates charge transport performance. Here, the advantage of this inverse relationship has been taken to fabricate flexible organic field effect transistors using ultraviolet irradiated regioregular (RR) and regiorandom (RRa) poly(3‐hexylthiophene) (P3HT) blend thin‐films as the device active layer. The blend films exhibit prominent charge carrier mobility up to 0.22 cm 2 V ‐1 s ‐1 . Even when the RR‐P3HT component comprises only a small proportion of the blend, vertical phase separation of the components ensures formation of effective charge transport pathways. The underlying mechanism is correlated to molecular self‐assembly of RR‐P3HT and its unfavorable intermolecular interactions with RRa‐P3HT. Transistor performance is retained upon application of high external strain and bending 1000 times. The top‐gate architecture enables the dielectric to serve as a self‐encapsulation layer to protect the underlying semiconductor from atmospheric oxygen and moisture, resulting in over 700 h ambient device stability. This facile blend approach is expected to be an alternative strategy for the fabrication of high performance flexible electronics.