High-performance and light-emitting n-type organic field-effect transistors based on dithienylbenzothiadiazole and related heterocycles

The high performance n-type field effect transistor (FET) characteristics and light-emitting properties of a dithienylbenzothiadiazole with trifluoromethylphenyl groups and the corresponding benzoselenadiazole and quinoxaline derivatives were investigated. FET devices with botton contact geometry were constructed by vapor-deposition on SiO₂/Si substrate and FET measurement were carried out at room temperature in a vacuum chamber without air exposure. The FET performance was optimized by fabricating the device with top contact geometry, where gold electrodes were defined after 50 nm of semiconductor deposition by using shadow masks. The electron mobility calculated in the saturation regime was 0.19 cm² V^-1S ^-1 at 80°C. The emission intensity is found to be increased with an increase in drain voltages due to the increased carrier recombination. The results show that the benzothiadiazole unit reduces the threshold voltage.