Electrodeposited poly(thiophene) thin film contacts for organic photovoltaics and organic light emitting diodes

We discuss a unique approach to the formation of hole-selective contacts on transparent conducting oxides, impacting both organic solar cell (OPV) and organic light emitting diode (OLED) technologies. We use electrodeposition, on activated and chemically modified indium-tin oxide (ITO) electrodes to grow poly(thiophene) (e.g. e-P3HT) films whose electrical properties and texturing at nanometer length scales is controlled by the electrodeposition protocol. Prior studies of OPVs created from these materials have been described in Chem. Mater. 2008, 20, 5796-5806. This talk will focus on the control of effective work function in e-P3HT films by control of counter ion placement and degree of formation of polaronic or bi-polaronic states, using photoemission spectroscopies. Changes in doping in these films has a profound effect on both turn-on voltages in OLEDs and fill-factors and series resistance in OPVs.