Molecular Locking with All-Organic Surface Modifiers Enables Stable and Efficient Slot-Die Coated Methyl-Ammonium-Free Perovskite Solar Modules.

The power conversion efficiency (PCE) of the state-of-the-art large area slot die-coated perovskite solar cells (PSCs) is now over 19%, but issues with their stability persist owing to significant intrinsic point defects and a mass of surface imperfections introduced during fabrication process. We report the utilization of a hydrophobic all-organic salt to modify the top surface of large area slot-die coated methylammonium (MA)-free halide perovskite layers. Bearing two molecules, each of which is endowed with anchoring groups capable of exhibiting secondary interactions with the perovskite surfaces, the organic salt acts as a molecular lock by effectively binding to both anion and cation vacancies, substantially enhancing the materials' intrinsic stability against different stimuli. It not only reduces the ingression of external species such as oxygen and moisture, but also suppresses the egress of volatile organic components during the thermal stability testing. The treated PSCs demonstrate efficiency of 19.28% (active area of 58.5 cm 2 ) and 17.62% (aperture area of 64 cm 2 ) for the corresponding mini-module. More importantly, unencapsulated slot-die coated mini-modules incorporating the all-organic surface modifier show ∼80% efficiency retention after 7,500 hours (313 days) of storage under 30% relative humidity (RH). They also remarkably retain more than 90% of the initial efficiency for over 850 hours while being measured continuously. This article is protected by copyright. All rights reserved.