A Microcontact-Printed Nickel-Passivated Copper Grid Electrode for Perovskite Photovoltaics

We report a novel transparent copper-based grid electrode fabricated by microcontact printing that offers high stability toward oxidation in air. Passivation is achieved using a 2.5 nm thick layer of nickel buried just below the surface of the copper film from which the grid is etched. This approach to electrode passivation retains the advantages associated with using microcontact printing lithography for grid fabrication of very fast resist deposition and compatibility with the low cost, low toxicity etchant ammonium persulfate. The processes of patterned resist deposition and metal etching is complete within less than 1 min. Using this approach, a grid electrode with a far-field transparency of 82% across the wavelength range 300–900 nm and a sheet resistance of 6.8 Ω sq−1 is demonstrated, which is shown to be a promising alternative to indium-tin oxide as the transparent electrode in perovskite photovoltaic devices.