Stability-improved organic n-channel thin-film transistors with nm-thin hydrophobic polymer-coated high-k dielectrics

Abstract

We report on the fabrication of N,N′-ditridecyl-perylene-3,4:9,10-tetracarboxylic diimide–C13 (PTCDI–C13), n-channel organic thin-film transistors (OTFTs) with 30 nm Al₂O₃ whose surface has been un-modified or modified with hexamethyldisilazane (HMDS) and thin hydrophobic CYTOP. Among all the devices, the OTFTs with CYTOP-modified dielectrics exhibit the most superior device performance and stability. The optimum post-annealing temperature for organic n-channels on CYTOP was also found to be as low as 80 °C, although the post-annealing was previously implemented at 120–140 °C for PTCDI domain growth in general. The low temperature of 80 °C hardly damages the CYTOP/n-channel organic interface which is deformed at a temperature higher than the glass transition temperature of CYTOP (∼110 °C). The pentacenequinone passivation layer turned out to be helpful to keep the interfacial trap density minimum, according to the photo-excited charge collection spectroscopy results for our 80 °C-annealed OTFTs with CYTOP-modified dielectrics.