Blade-Coating Perovskites for Tandem Devices: Liquid Mechanism, Film Formation, and Performance

Perovskite solar cells have achieved a high efficiency and exhibited great potential for commercialization. Blade- and slot-die-coating techniques are regarded as the most competitive approaches for the future industrialization due to their capability for large-area fabrication. In contrast to the simple spin-coating method employed in lab-scale fabrication, the blade- and slot-die-coating techniques involve complex fluid dynamics and film growth processes, thereby leading to inferior film quality and device performance. In this review, we comprehensively analyze the influence of fluid mechanisms involved in all the blade-coating process and summarize the key points for preparing large-scale and uniform perovskite films. Subsequently, we highlight the influence of different solvent extraction techniques on the nucleation and crystallization processes of perovskite films. Moreover, a comprehensive assessment is performed to present the current states and challenges faced by both single-junction wide- and narrow-bandgap solar cells as well as all-perovskite tandem solar cells. Finally, we present a discussion aimed at advancing the development of large-area perovskite solar cells.