High-κ organometallic lanthanide complex as gate dielectric layer for low-voltage, high-performance organic thin-film transistors

Low-voltage pentacene-based organic thin-film transistors (OTFTs) have been fabricated using the high-κ organometallic lanthanide complex, Tb(tta)₃L_2NR (tta = 2-thenoyltrifluoroacetonate, L_2NR = (−)-4, 5-pinene bipyridine) as the gate dielectric material. The optimized gate insulator exhibits a low leakage current density of < 10⁻⁷ A cm⁻² under bias voltage of − 5 V, a smooth surface with RMS of about 0.40 nm, a high capacitance of 43 nF cm⁻² and an equivalent κ value of 7. The obtained OTFTs show high electric performance with carrier mobility of 0.20 cm² V⁻¹ s⁻¹, on/off ratio of 4 × 10⁵, threshold voltage of − 0.6 V, and subthreshold slope of 0.7 V dec⁻¹ when operated at − 5 V. The results demonstrate the organometallic lanthanide complex is a promising candidate as gate insulator for low-voltage OTFTs. - Highlights: • Transistors with organometallic lanthanide complex films have high capacitance density. • Device performance highly depends on the properties of dielectric surfaces. • The optimized transistors can well work at − 5 V and exhibit good performance.