Dielectric tuning strategies for flexible display backplane transistors

Organic, polymer, and oxide-based transistors are among the alternatives to silicon being considered for flexible display pixel circuitry. Carrier mobilities in the semiconductors now exceed those of amorphous silicon, and switching voltages can be below 2 V. In this presentation, we focus on gate dielectrics compatible with these semiconductors. First, we consider polymer dielectrics in which static charge is implanted during device fabrication. Carrier energy levels are markedly and predictably altered by static charge embedded in polystyrene films adjacent to organic semiconductors, and multiple device activities can be obtained from a single device layout using one semiconductor. Second, we describe progress using ionically intercalated solution-processed alumina dielectrics, in which high capacitance is obtained from charge migration through channels in the oxides. The latter dielectrics greatly decrease switching voltages compared to other oxide and polymer dielectrics, and can be used with both organic and oxide semiconductors.