Three-Dimensional Nanostructured Indium-Tin-Oxide Electrodes for Enhanced Performance of Bulk Heterojunction Organic Solar Cells

A three-dimensional indium tin oxide (ITO) nanohelix (NH) array is presented as a multifunctional electrode for bulk heterojunction organic solar cells for simultaneously improving light absorption and charge transport from the active region to the anode. It is shown that the ITO NH array, which is easily fabricated using an oblique-angle-deposition technique, acts as an effective antireflection coating as well as a light-scattering layer, resulting in much enhanced light harvesting. Furthermore, the larger interfacial area between the electrode and the active layer, together with the enhanced carrier mobility through highly conductive ITO NH facilitate transport and collection of charge carriers. The optical and electrical improvements enabled by the ITO NH electrode result in a 10% increase in short-circuit current density and power-conversion efficiency of the solar cells.