The Influence of the Electrode Choice on the Performance of Organic Solar Cells

This chapter gives an overview of the relevant issues on choice of electrodes for different types of solar cells, and mechanisms relevant to electrode choice that affect solar cell performance. The issues for the electrode choice are discussed for Schottky barrier, heterojunction, and dye-sensitized solar cells. For each of the device types, recommendations on the electrode choice are given, and an overview of commonly used electrode materials is provided. Special attention is devoted to indium tin oxide (ITO) since it is the most commonly used electrode in organic optoelectronic devices. Influence of the various surface treatments of ITO on its properties and the solar cell performance are discussed in detail. Various additional layers which can be introduced into the structure to modify the anode 454or cathode contact, such as PEDOT:PSS, BCP, and LiF, are also discussed. The performance of the solar cell is typically strongly dependent on the thickness of any layers introduced into the structure to modify the electrodes, so that the thicknesses of these layers should be optimized to avoid deterioration of the performance due to increased series resistance of the solar cell.