One-Step Slot-Die Coating Deposition of Wide-Bandgap Perovskite Absorber for Highly Efficient Solar Cells

Slot-die coating is a promising technique paving the way for large-area perovskite deposition and commercially relevant solar device fabrication with sharp control over the thickness and material composition. However, before transferring perovskite solar cells technology to commercial applications, it is required to develop ink formulations, guaranteeing high homogeneity over a wide surface and leading to large, defect-free, and well-crystallized perovskite grains to maximize the device performances. A one-step slot-die deposition route, combining ink tailoring and vacuum aspiration solvent extraction, affording the deposition of a high-bandgap multication perovskite, is reported. One important key is the introduction of methylammonium chloride in the ink formulation, which substantially enhances the film quality over a large area. Although the efficacy of antisolvent dripping is demonstrated on a small area, it is not compatible with larger areas. This work compares the latter with a vacuum quench protocol, allowing efficient extraction of the solvents. Considering both ink formulation engineering and vacuum solvent extraction, a stabilized power conversion efficiency of up to 17.5% is reached. This constitutes, to the best of our knowledge, the highest reported value for a high-bandgap absorber deposited by slot-die coating. Moreover, stability over 180 h under maximum power point conditions is herein demonstrated.