The effect of surface polarity of gate dielectric buffer layer on operational stability in organic thin film transistors

We studied the effect of surface polarity of gate dielectric buffer layer on operational stability in organic thin film transistors (OTFTs). By employing four types of polymers with different polarity, we found out the operational stability of OTFTs can be improved with low-polarity polymer gate dielectric buffer layer. With low-polarity polymers, the devices showed good operational stability with longer relaxation time than 10⁶ sec. Also, threshold voltage of the devices shifted less than 2 V under high gate bias stress of 3 MV/cm for two hours. Good stability may be resulted from low surface trap density as well as good grain interconnection of pentacene on low-polarity polymer.