Microwave Annealing-Enabled Defect Healing for High-Performance and Stable Organic Transistors and Circuits

Organic field-effect transistors (OFETs) are promising candidates for use in next-generation electronic devices. However, organic semiconductors (OSCs) exhibit low crystallinity and weak van der Waals (vdW) forces, which makes them prone to defect formation, resulting in localized states in the bandgap that can trap charge carriers. This seriously limits the performance and stability of OFETs, which typically exhibit high contact resistance (R_c) and poor operational stability. It is highly desirable, but challenging, to eliminate defects in OSCs. Herein, a microwave annealing strategy is presented that heals defects in OSCs near the electrode/OSC interface through co-associated high-frequency vibration. By using this technique, the trap density of states (DOS) is significantly reduced and coplanar OFETs achieve an ultralow R_c·W of 20 Ω cm and a high mobility of 10.57 cm² V^-1 s^-1. Moreover, the on-state current of the OFET retained 99% of its initial value after 10 000 s of constant bias stress, and the switching voltage of the biased-load inverters hardly shifted after cycle tests, demonstrating excellent operational stability. The high-efficiency, uniform heating, and low-temperature processing strategy has great application prospects in organic devices and circuits.