Gate dielectric materials for high-mobility organic transistors of molecular semiconductor crystals

High-mobility organic single-crystal transistors are constructed with silicon dioxide, a polymeric insulator (polyvinylphenol), and an organic insulating single-crystal (diphenylanthracene). All the single-crystal devices show high-mobility μ exceeding 10 cm2/V s with relatively low-density carriers of ∼1011 cm−2, though μ is significantly reduced at one-order higher carrier density. Among the three, the diphenylanthracene device holds relatively high-mobility even at carrier density of ∼1012 cm−2, so that it realizes the maximum conductivity ever achieved for organic transistors. Employing simultaneous measurements of Hall-effect and conductivity of the field-effect carriers, the result is attributed to different extent of randomness in the surface potential on the gate insulators.