Low-Voltage Organic Field-Effect Transistors Using a Phosphocholine-Based Polyampholyte Dielectric

Low-voltage organic field-effect transistors (OFETs) are of great significance for realizing low power-consumption electronics, where increasing the dielectric constant of gate dielectrics is an effective strategy to achieve low-voltage operation. Herein, a series of polyampholyte dielectrics with pendant phosphocholine zwitterionic groups are synthesized, and their applications in OFET devices are systematically studied. The dielectric constant of phosphocholine-based polyampholyte (P-PA) can reach 6.0, and the OFET performances based on P-PA dielectrics are greatly improved. Specifically, devices using P-PA-20 that contains 20 mol % zwitterionic groups as the dielectric layer, show the best performance, boosting a three-orders-of-magnitude increase in mobility and decreasing the threshold voltage (V_th) to a value as low as 0.07 V compared with devices using the control dielectric without zwitterionic groups. In addition, the corresponding P-PAs exhibit excellent flexibility, with both high tensile strength exceeding 20 MPa and high elongation at break exceeding 400%. This study provides a novel method to construct polymeric dielectrics with a high dielectric constant, which may be further exploited to improve OFET device performance and be instructive for the design of new materials for future use in flexible/stretchable and wearable electronic devices.