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 degrees C, although the post-annealing was previously implemented at 120-140 degrees C for PTCDI domain growth in general. The low temperature of 80 degrees C hardly damages the CYTOP/n-channel organic interface which is deformed at a temperature higher than the glass transition temperature of CYTOP (similar to 110 degrees 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 degrees C-annealed OTFTs with CYTOP-modified dielectrics.