Injection-induced De-doping in a conducting polymer during device operation: Asymmetry in the hole injection and extraction rates

A mechanism is described that can alter the doping level of conducting polymers during normal electrical injection, which arises from differential charge extraction/injection into transport sites, and which is likely to be an intrinsic feature of the hopping transport itself. This and not Joule heating is the cause of the conductance decay in PEDT:PSS at strong electrical injection, in which the polyelectrolyte counter-ion also plays a key role. Neutral (non-acidic) PEDT:PSS is more stable in this regard.