High mobility solution-processed n-channel organic thin film transistors

N-channel organic thin-film transistors (OTFTs) based on N,N'-bis(n-octyl)-(1,7&1,6)-dicyanoperylene-3,4:9,10-bis(dicarboximide) (PDI8-CN₂) were fabricated using different semiconductor film deposition methods, dielectric materials, and device structures. It was found that top -contact OTFTs fabricated on Si-SiO₂ substrates with drop-cast or vapor deposited films afford comparable electron mobilities (0.01-0.1 cm²/Vs), much larger than those based on spincoated PDI8-CN2 films (0.001 cm²/Vs). Furthermore, n-channel top-contact TFTs were fabricated using solution-processed PDI8-CN₂ films and a UV-curable solution-processed polymeric dielectric. These devices exhibit typical gate leakage currents < 1nA for V_gate > 100V, which are negligible compared to the corresponding source/drain currents (> 0.1mA). OTFTs tested in ambient exhibit electron mobilities as high as 0.05-0.2 cm ²/Vs and I_on:I_off ∼ 10⁵. Furthermore, I_souroe-drain-V_gate hysterisis is negligible when the OTFTs were tested in both bias directions at different V_gate scan rates, demonstrating excellent insulator-semiconductor interfacial properties. Bottom-contact TFTs exhibit typical lower performance (∼ ×0.1)compared to the top-contact structure. All of the devices stored in air for several months exhibit no degradation of the device characteristics.