The origin of the high conductivity of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT- PSS) plastic electrodes

The development of printed and flexible (opto)electronics requires specific materials for the device's electrodes. Those materials must satisfy a combination of properties. They must be electrically conducting, transparent, printable, and flexible. The conducting polymer poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) is known as a promising candidate. Its conductivity can be increased by 3 orders of magnitude by the secondary dopant diethylene glycol (DEG). This secondary doping phenomenon is clarified in a combined photoelectron spectroscopy and scanning probe microscopy investigation. PEDOT-PSS appears to form a three-dimensional conducting network explaining the improvement of its electrical property upon addition of DEG. Polymer light emitting diodes are successfully fabricated using the transparent plastic PEDOT-PSS electrodes instead of the traditionally used indium tin oxide.