Cost-effective ITO-free organic solar cells with silver nanowire–PEDOT:PSS composite electrodes via a one-step spray deposition method

We demonstrate cost-effective, indium tin oxide (ITO)-free organic solar cells (OSCs) fabricated with a silver nanowire (AgNW)–poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) composite electrode. The composite films were prepared with a one-step spray-coating of a mixture composed of AgNW and a highly conductive, dimethylsulfoxide (DMSO)-treated PEDOT:PSS (hcPEDOT). The film-thickness, optical transmittance, and sheet resistance of AgNW–hcPEDOT hybrid electrodes were easily controlled by varying the spray deposition time. With AgNW–hcPEDOT composite electrodes, the devices exhibited high power conversion efficiencies of up to 2.16% under 100 mW cm−2 and AM 1.5G illumination conditions. In addition, the surface of the AgNW–hcPEDOT composite electrodes was further smoothened with an additional spray-coated PEDOT:PSS buffer layer, leading to reduced shorting and improved cell-efficiency. As a result, the best performing devices with a AgNW–hcPEDOT electrode and spray-coated PEDOT buffer exhibited efficiencies of up to 2.65%, which approaches that of conventional ITO-based devices. These results indicate that the one-step spray-coated AgNW–hcPEDOT composite-based film is a viable alternative to the high-cost and vacuum-deposited ITO for mass-production and low-cost roll-to-roll based solar cells.