Highly stable, low-voltage operable high-mobility flexible organic thin-film transistors based on a tri-layer gate dielectric

Abstract

The application fields of organic thin-film transistors (OTFTs) depend on their field-effect mobility (μ). The low-voltage operation and good operating stability are the prerequisites for the practical applications of OTFTs. To date, it is still a huge challenge to obtain low-voltage operable OTFTs with high μ and good operating stability at the same time. In this work, we elaborately design and process a tri-layer gate dielectric, for pursuing the low-voltage operable, high-performance flexible OTFTs. The effects of the gate dielectrics on the device performances and the relevant mechanisms are discussed in detail. The tri-layer gate dielectric has a large gate capacitance per unit area, and simultaneously suppresses the polarization effect of the gate dielectric and the charge trapping at the interface and bulk of the gate dielectric, by which both the μ and the operating stability are significantly improved. As a result, the flexible OTFTs exhibit excellent figures of merit at low operating voltages below 4 V, with high μ up to 2.6 cm2 Vs−1, good bias stress stability with a negligible change of the channel current for 5000 s, and good mechanical flexibility with a negligible performance degradation after the tension bending for 1000 times at small curvature radii of both 5.0 mm and 3.0 mm in sequence. Our works provide a strategy for developing the high-performance flexible OTFTs with low-voltage operation, high μ and good operating stability simultaneously.