Organic thin-film field-effect transistors with MoO3/Al electrode and OTS/SiO2 bilayer gate insulator

An organic thin-film transistor (OTFTs) having OTS/SiO2 bilayer gate insulator and MoO3/Al electrode configuration between gate insulator and source–drain (S–D) electrodes has been investigated. Thermally grown SiO2 layer is used as the OTFT gate dielectric and copper phthalocyanine (CuPc) for an active layer. We have found that using silane coupling agents, octadecyltrichlorosilane (OTS) on SiO2, surface energy of SiO2 gate dielectric is reduced; consequently, the device performance has been improved significantly. This OTS/SiO2 bilayer gate insulator configuration increases the field-effect mobility, reduces the threshold voltage and improves the on/off ratios simultaneously. The device with MoO3/Al electrode has similar source–drain current (IDS) compared to the device with Au electrode at same gate voltage. Our results indicate that using double-layer of insulator and modified electrode is an effective way to improve OTFT performance.