Fabrication of anode and cathode layers for back-contact solar cells by microsphere lithography

The concept of back-contact device architecture for perovskite solar cells (PSCs) is a promising alternative to PSCs with the traditional sandwich-type device architecture. The most convenient and low cost method to fabricate back-contact electrodes for PSCs is using microsphere lithography as it can be performed without expensive photolithography tools and cleanroom environment. Deposition of a monolayer of polystyrene microbeads on the surface of cathode substrates (conductive transparent oxide glass substrates covered with a thin layer of SnO₂) is achieved through a self-assembly process. The self-assembly process is based on electrostatic attraction forces between negatively charged microbeads and the positively charged cathode surface. The self-assembled monolayer of polystyrene microbeads is used as a sacrificial polymer mask to fabricate the anode layer on top of cathodes. The back-contact electrodes are obtained after removing the sacrificial polymer mask through a lift-off process.