π‐σ‐Phosphonic Acid Organic Monolayer/Sol–Gel Hafnium Oxide Hybrid Dielectrics for Low‐Voltage Organic Transistors

Anthryl-alkyl-PA (π-σ-PA) self-assembled monolayers (SAMs)/hafnium oxide (HfO2) hybrid dielectrics have been integrated into organic thin film transistors (OTFTs) to achieve operating voltages under −1.5 V. Using π-σ-PA SAMs on sol–gel processed HfO2, pentacene-based OTFTs possess low subthreshold slopes (100 mV dec−1), high on–off current ratios (105–106), and hole mobilities as high as 0.22 cm2 V−1 s−1.