TCAD simulation of organic field-effect transistors based on spray-coated small molecule organic semiconductor with an insulating polymer blend

A commercial TCAD tool (Silvaco-Atlas) is used for the simulation of organic field-effect transistor (OFET) devices based on sprayed 6,13-bis(triisopropylsilylethynyl)-pentacene (TIPS-Pentacene) organic semiconductor and polystyrene (PS) insulating polymer blends (0.8:0.2 w/w). The simulation results are validated and improved after systematic comparison with experimental data. Shallow donor-like bulk and interface traps density of states (DOS) are taken into account for better convergence with the experimental data. Also, the necessity to include negative interface charge density was revealed. Furthermore, the constant low-field mobility model as well as the band-to-band tunneling model were selected, while their parameters were properly adjusted. Simulated electrical characteristics and experimental data demonstrate a very good agreement but necessitate further improvement. The important physical quantity of root-mean-square (RMS) roughness at the TIPS-Pentacene/PS interface is also included in the simulation considering various patterns. Different levels of RMS roughness at the active interface and different patterns are considered. Also, the TIPS-Pentacene thickness non-uniformity was examined, and the simulation results suggest that it is more significant when the TIPS-Pentacene thickness is thinner near the drain electrode side. Finally, the effects of non-uniformity on the device's overall electrical behavior are systematically investigated.