Photoresponsive characteristics and hysteresis of soluble 6,13-bis(triisopropyl-silylethynyl)-pentacene-based organic thin film transistors with and without annealing

We report on the photoresponsive characteristics and hysteresis of soluble 6,13-bis(triisopropyl-silylethynyl; TIPS)-pentacene-based organic thin film transistors (OTFTs) with and without an annealing process. Under incident light, the hysteresis and memory effect increased for the annealed devices through photoinduced electron trapping and recombination at the gate-dielectric- semiconductor interface. To investigate the cause of the photoenhanced memory effect and hysteresis, we estimated the trapped electron densities from the threshold shift, while applying a gate bias to the annealed OTFTs under both dark and light conditions. A comparison of the characteristics of OTFT devices that are prepared under various conditions suggests that deep electron traps might be caused by the appearance of a domain boundary (i.e., cracks) in the annealed TIPS-pentacene film during the annealing process, which showed stable photoresponsive characteristics but relatively lower mobility.