Effects of concentration on charge trapping in polymer electrets with aryl-amine donors.

Thin film polymer dielectrics with controllable electronic properties are of considerable interest for applications in organo-electronic systems. We use aryl-amines in thin film polystyrene dielectrics to modify electron and hole trap states and densities. When introduced as free additives in blends as well as when chemically bound to polymers, these moieties induce changes in static potential differences that modify the behavior of adjacent electronic materials. The aryl-amines contribute to the charge storage capacity of the system and lower operational threshold voltages, on the order of thirty volts ΔV_th =O(30V), for devices after the application of static charging fields as measured in pentacene-based organic field effect transistors. Films with free additives showed a strongly concentration dependent stability in ΔV_th and this behavior was corroborated by polymers with tethered amines. Stability is higher at lower amine-concentrations suggesting that inter-amine distance is an important effect in these systems.