Flexible organic field-effect transistors with high-reliability gate insulators prepared by a room-temperature, electrochemical-oxidation process

Abstract

Flexible organic field-effect transistors (OFETs) with electrochemically oxidized gate insulators (AlO_x:Nd) covered by a thin layer of hydroxyl-free poly(perfluorobutenylvinylether) known as Cytop were fabricated on a polyethylene naphthalate (PEN) substrate. The AlO_x:Nd/Cytop bilayer insulator exhibited excellent insulating properties with low leakage current, high dielectric constant, high breakdown field, and low surface roughness. The pentacene film on AlO_x:Nd without Cytop consisted of small grains, while the one on AlO_x:Nd with Cytop exhibited a dendritic structure with a larger average grain size of ∼350 nm. The pentacene OFET with Cytop exhibited higher mobility (0.75 cm² V⁻¹ s⁻¹) and better electrical stability under gate-bias-stress (in air condition) compared to that without Cytop. In addition, the flexible OFET was able to maintain a relatively stable performance under a certain degree of bending.