Performance improvement of organic thin film transistors by using active layer with sandwich structure

We report organic thin film transistors (OTFTs) with pentacene/fluorinated copper phthalo-cyanine (F 16 CuPc)/pentacene (PFP) sandwich configuration as active layers. The sandwich devices not only show hole mobility enhancement but also present a well control about threshold voltage and off-state current. By investigating various characteristics, including current-voltage hysteresis, organic film morphology, capacitance-voltage curve and resistance variation of active layers carefully, it has been found the performance improvement is mainly attributed to the low carrier traps and the higher conductivity of the sandwich active layer due to the additional induced carriers in F 16 CuPc/pentacene. Therefore, using proper multiple active layer is an effective way to gain high performance OTFTs.