Flexible polymer light-emitting diodes (see photo) are fabricated using highly conductive vapor-phase polymerized poly(3,4-ethylenedioxythiophene) (VPP PEDOT) as an anode material. The influence of the VPP PEDOT film thickness and the effects of thermal annealing and oxygen-plasma treatment on conductivity, work function, and optical transmission are explored and used to optimize device performance, resulting ultimately in devices that have efficiencies comparable to those with indium tin oxide anodes.