A matter of drying: Blade-coating of lead acetate sourced planar inverted perovskite solar cells on active areas >1 cm2
Among various coating techniques, blade coating is one promising alternative for upscaling perovskite photovoltaic devices from small area research cells to intermediately sized cells and modules. Also, it is potentially compatible for future roll-to-roll processing. In this work, planar inverted (p-i-n) solution-processed perovskite solar cells are presented, with absorber layers deposited via blade coating in a one-step process, employing lead(II) acetate trihydrate as lead source. It is found that control of the perovskite layer drying before annealing is most critical for device function. Various drying approaches by temperature and/or blowing with a directed nitrogen stream are compared and demonstrate a large impact on device performance. Whereas drying without additional gas flow leads to chaotic morphologies, inhomogeneous layers, and low power conversion efficiencies, controlled drying with a directed nitrogen stream results in power conversion efficiencies of up to 11.8% for devices with an active area of 1.1 cm2. In comparison, solar cells with spin-coated absorber layers achieve an efficiency of 14.3% on small areas. Detailed analyses using photoluminescence spectroscopy, X-ray diffraction, and scanning electron microscopy reveal a strongly enhanced layer quality and crystallinity for the actively dried perovskite layers, leading to enhanced device performance.