Ultrathin Transparent Au Electrodes for Organic Photovoltaics Fabricated Using a Mixed Mono‐Molecular Nucleation Layer

Abstract

AbstractA rapid, solvent free method for the fabrication of highly transparent ultrathin (∼8 nm) Au films on glass has been developed. This is achieved by derivatizing the glass surface with a mixed monolayer of 3‐mercaptopropyl(trim­ethoxysilane) and 3‐aminopropyl(trimethoxysilane) via co‐deposition from the vapor phase, prior to Au deposition by thermal evaporation. The mixed mono­layer modifies the growth kinetics, producing highly conductive films (∼11 Ω per square) with a remarkably low root‐mean‐square roughness (∼0.4 nm) that are exceptionally robust towards UV/O3 treatment and ultrasonic agitation in a range of common solvents. As such, they are potentially widely applicable for a variety of large area applications, particularly where stable, chemically well‐defined, ultrasmooth substrate electrodes are required, such as in organic optoelectronics and the emerging fields of nanoelectronics and nanophotonics. By integrating microsphere lithography into the fabrication process, we also demonstrate a means of tuning the transparency by incorporating a random array of circular apertures into the film. The application of these nanostructured Au electrodes is demonstrated in efficient organic photovoltaic devices where it offers a compelling alternative to indium tin oxide coated glass.