Power-efficient and high-performance potential of pentacene transistors enabled by metal-nitride gate insulators fabricated with nitrogen plasma

Abstract

The demand for next-generation organic field-effect transistors (OFETs) with low operating voltage is becoming gradually attractive in many application areas, such as flexible/wearable medical sensors and stretchable electronics. While using high dielectric materials is a potent approach, it often results in a decline in field-effect mobility or on/off ratio. Unfortunately, achieving low-voltage operation has hindered practical applications, compromising device performance. Here, we discovered for the first time a novel class of low-driving voltage pentacene transistors adopting gate insulators composed of nitrogen-plasma-reacted AlN_x, TiN_x, and TaN_x. This exciting discovery is simple, affordable, environmentally friendly, and secure. X-ray photoelectron spectrometer (XPS) analysis reveals that the as-formed metal nitrides are composited with certain native oxide components, exhibiting outstanding leakage current blocking capacity and a high dielectric constant. Further, the surface energy of metal nitrides was altered by applying a thin layer of poly-(4-vinylphenol) (PVP). This modification improved the growth of pentacene grains and the insulator/pentacene interface. The best devices by comprehensive evaluation, the TiN_x samples, achieve a high average of field-effect mobility ∼1.41 cm²/Vs, a subthreshold swing of 0.19 V/dec, an on/off current ratio of ∼10⁴, and a turn-on voltage close to 0 V, which shows promising potential candidates for the flexible electronic devices, optoelectronic devices, and neuromorphic application.