Low-voltage high-performance C₆₀ thin film transistors via low-surface-energy phosphonic acid monolayer/hafnium oxide hybrid dielectric

C₆₀-based organic thin film transistors (OTFTs) have been fabricated using a n-octadecylphosphonic acid self-assembled monolayer/sol-gel processed hafnium oxide hybrid dielectric. With the combination of high capacitance (580 nF/cm²) and low leakage current density (8×10^-9 A/cm²), this hybrid dielectric yields C₆₀ OTFTs operating under 1.5 V with an average n-channel saturation field-effect mobility of 0.28 cm²/V s, high on-off current ratio of 10⁵, and low subthreshold slope of 100 mV/decade. The low surface energy of the n-octadecylphosphonic acid allows C₆₀ to form a thin film with large grains that provide an efficient charge carrier pathway for the low-voltage OTFTs.