Thermal annealing effect on the crack development and the stability of 6,13-bis(triisopropylsilylethynyl)-pentacene field-effect transistors with a solution-processed polymer insulator

We report the thermal annealing effect on the mobility enhancement, the crack development, and the stability of 6,13-bis(triisopropylsilylethynyl) (TIPS)-pentacene field-effect transistors (FETs) with a solution-processed polymeric insulator. A high value of the field-effect mobility (0.401 cm2/V s) is achieved by thermally annealing the TIPS-pentacene FET at 60 °C which corresponds to the baking temperature of the TIPS-pentacene film. We demonstrate that thermal cracks, resulting primarily from side chains of the TIPS-pentacene, play a critical role on the degradation of the electrical properties of TIPS-pentacene FET, particularly in air under atmospheric pressure. The annealing effect is found to suppress both the development of the cracks and the increase of the off-current with time in the ambient environment. It is suggested that the cracks act as trapping sites of moisture and/or oxygen for the off-current flow and thus deteriorate the electrical performances of the TIPS-pentacene FET.