One-step deposition by slot-die coating of mixed lead halide perovskite for photovoltaic applications

•Perovskite can be deposited in one-step using slot-die coating.•Slot-die coating is a roll to roll compatible printing method.•A pre-heated substrate promotes horizontal crystal growth.•Application of a cold air-knife reduces the film roughness.•Comparable performance to spin coated devices is achieved.

Recent advances in the performance and stability of lead halide perovskite solar cells announce a promising future for this technology. As the understanding of lab scale device fabrication progresses technology developments in the area of up-scaling are required to demonstrate their viability on an industrial and pre-commercial scale. These developments include replacing slow spin coated deposition techniques with continuous roll to roll compatible slot-die methods. In this work we demonstrate the suitability of a one-step slot-die coating method for the deposition of lead halide perovskite layers, in particular for infiltration into a mesoporous titania scaffold. Appropriate crystallisation dynamics of the perovskite are achieved by careful control of the substrate temperature in combination with a post-processed rapid air knife application. We show that devices fully processed in air using this method deliver a photovoltaic conversion efficiency up to 9.2%, this is comparable to those manufactured using a spin coating process.