Condensation Coefficient Modulation: An Unconventional Approach to the Fabrication of Transparent and Patterned...

Silver is the metal of choice for the fabrication of highly transparent grid electrodes for photovoltaics because it has the highest electrical conductivity among metals together with high stability toward oxidation in air. Conventional methods for fabricating silver grid electrodes involve printing the metal grid from costly colloidal solutions of nanoparticles, selective removal of metal by etching using harmful chemicals, or electrochemical deposition of the silver, an inherently chemical intensive and slow process. This Spotlight highlights an emerging approach to the fabrication of transparent and patterned silver electrodes that can be applied to glass and flexible plastic substrates or directly on top of a device, based on spatial modulation of silver vapor condensation. This counterintuitive approach has been possible since the discovery in 2019 that thin films of perfluorinated organic compounds are highly resistant to the condensation of silver vapor, so silver condenses only where the perfluorinated layer is not. The beauty of this approach lies in its simplicity and versatility because vacuum evaporation is a well-established and widely available deposition method for silver and the shape and dimensions of metallized regions depend only on the method used to pattern the perfluorinated layer. The aim of this Spotlight is to describe this approach and summarize its electronic applications to date with particular emphasis on organic photovoltaics, a rapidly emerging class of thin-film photovoltaics that requires a flexible alternative to the conventional conducting oxide electrodes currently used to allow light into the device.