High-mobility pentacene organic thin-film transistors achieved by reducing remote phonon scattering and surface-roughness scattering

[Display omitted] •The RPS and SRS greatly impact on the carrier mobility of OTFTs.•The interaction distance between remote phonons and carriers is above 150 nm.•The carrier mobility of pentacene OTFTs on Si substrate reaches 10.6 cm2 V−1 s−1.•The carrier mobility of 7.99 cm2 V−1 s−1 is achieved on flexible PI substrate. Pentacene organic thin-film transistors (OTFTs) with very high carrier mobility have been achieved on both rigid and flexible substrates by using high-k gate dielectric and metal gate. The high-k gate dielectric with suitable thickness can reduce the surface-roughness scattering, while the metal gate can suppress the remote phonon scattering. As a result, based on NbLaO gate dielectric, OTFTs with high carrier mobility of 10.6 cm2 V−1 s−1 (7.99 cm2 V−1 s−1) with the capacitance per unit area measured at frequency of 1 kHz and small threshold voltage of −0.92 V (−0.74 V) fabricated on Pd-coated Si substrate (Pd-coated vacuum tape) are realized, though they have rougher dielectric surface and smaller pentacene grains than their counterparts fabricated on n-Si substrate. Moreover, with the addition of 13-nm SiO2 interlayer between the NbLaO gate dielectric and metal gate electrode, the carrier mobility decreases by 71% and 65% for the OTFTs on Si and V.T. substrates, respectively, highlighting the importance of the RPS.