The performance of a flexible transparent conductive electrode with extremely smooth topography capable of withstanding thermal processing at 300 degrees C for at least 6 h with little change in sheet resistance and optical clarity is reported. In depth investigation is performed on atomic layer deposition (ALD) deposited ZnO on Ag nanowires (NWs) with regard to thermal and atmospheric corrosion stability. The ZnO coated nanowire networks are embedded within the surface of a polyimide matrix, and the <2 nm roughness freestanding electrode is used to fabricate a white polymer light emitting diode (PLED). PLEDs obtained using the ZnO-AgNW-polyimide substrate exhibit comparable performance to indium tin oxide (ITO)/glass based devices, verifying its efficacy for use in optoelectronic devices requiring high processing temperatures.