High-performance solution-processed low-voltage polymer thin-film transistors with low-k/High-k bilayer gate dielectric

Solution-processed low-voltage organic thin-film transistors (OTFTs) were fabricated using the high-mobility donor-acceptor copolymer semiconductor indacenodithiophene-co-benzothiadiazole (IDTBT) and large permittivity (high-k) relaxor ferroelectric polymer poly (vinylidene fluoride-trifluoroethylene-chlorofloroethylene). It is shown that, with the face-on molecule packing in as-deposited IDTBT films, the close interfacing between the backbone and the dielectric layer causes significant mobility degradation of the fabricated OTFTs due to dipole effects. By inserting a thin, low-polar dielectric layer between the high-k one and the channel, the dipole field can be effectively screened and the devices present a high mobility similar to that of previously reported high-voltage IDTBT OTFTs. With the bilayer gate dielectric and the IDTBT semiconductor, low-voltage OTFTs are achieved with the average mobility of 1.4 cm²/V·s and ON/OFF-current ratio larger than 10⁶ , which is among the best reported performance so far for solution processed low-voltage OTFTs.