High-k polymer materials containing cyclic carbonate as gate dielectrics for application in low-voltage operating organic thin-film transistors†
Low-voltage operation in organic thin-film transistors (OTFTs) is desirable for low power applications and portable electronics. Using polymer materials with a high dielectric constant (high-k) as gate dielectrics is an important way to realize low-voltage operating OTFTs. In this work, we synthesized a class of novel copolymers, which exhibit a high-k up to 7–10 depending on the content of cyclic carbonate. These copolymer materials are easily processed into films with a smooth surface topography and without pinholes by simple spin-coating. Moreover, they show excellent insulation properties with low leakage current densities (<7 × 10−7 A cm−2 at 100 MV m−1) and small dielectric loss (<0.03, 102–105 Hz). Meanwhile, cross-linked copolymers also display good flexibility and solvent resistance. To inspect their application prospects in low-voltage operating OTFTs, these copolymer films were employed as gate dielectrics to build p- and n-type OTFTs with C10-DNTT and F16CuPc as active layers, respectively. As a result, our OTFTs exhibit good field-effect properties at low operating voltages below 10 V, with high hole and electron mobility up to 9.7 and 0.005 cm2 V−1 s−1 on average, respectively. Our results indicate a strategy on design of high-k polymer materials as gate dielectrics to pursue low-voltage operating OTFTs.