Ultrasonic spray coating for the scalable fabrication of Perovskite-on-Chalcogenide monolithic tandem Devices: Approaching the 20% efficiency

The combination of perovskite and chalcogenide solar cells allows for the monolithic fabrication of all-thin-film tandem with compositional tunability, facilitating optimal band gap alignment for an efficient absorption of the sunlight spectrum, while empowering flexible photovoltaic applications. However, this combination is yet to reach the levels of efficiency and production scalability seen in perovskite/silicon tandems, mostly due to the challenging fabrication of perovskite cells on top of the irregular chalcogenide cell surface. Herein, we propose to enhance the scalability of the technology by developing the ultrasonic spray coating of perovskite on top of Cu(In,Ga)S(Se) (CIGS) cells for the fabrication of monolithic tandem devices. The capability of the technique to deposit conformal perovskite coatings, aligned with interlayer optimization, results in the successful integration of perovskite and chalcogenide cells. The resulting monolithic tandem devices exhibit efficiencies close to 20%, a significant improvement on the efficiency of the single junction perovskite and CIGS reference cells. These results offer a promising pathway towards the upscaling of perovskite/CIGS device fabrication.