ZnO based field-effect transistors (FETs): solution-processable at low temperatures on flexible substrates

A well-performing ZnO field-effect transistor (FET) on poly-ethylenenaphthalate (PEN) foil with solution-processed ZnO semiconductor and dielectric material is presented for the first time. In addition, we developed a route that allows preparation of the ZnO semiconductor layer simply from commercially available ZnO dissolved in aqueous ammonia in a single processing step. The material performance in FETs exceeds that of state of the art solution-processable ZnO materials at comparably low processing temperatures (<150 degrees C). Polysilsesquioxanes are identified as physically and chemically suitable dielectric materials that also fulfill the criteria solution processability at low temperatures. Water and ethyllactate are used as "green'' solvents.