To upscale the emerging perovskite photovoltaic technology to larger-size modules, industrially relevant deposition techniques need to be developed. In this work, the deposition of tin oxide used as an electron extraction layer is established using chemical bath deposition (CBD), a lowcost and solution-based fabrication process. Applying this simple lowtemperature deposition method, highly homogeneous SnO 2 films are obtained in a reproducible manner. Moreover, the perovskite layer is prepared by sequentially slot-die coating on top of the n-type contact. The symbiosis of these two industrially relevant deposition techniques allows for the growth of high-quality dense perovskite layers with large grains. The uniformity of the perovskite film is further confirmed by scanning electron microscopy (SEM)/scanning transmission electron microscopy (STEM) analysis coupled with energy dispersive X-ray spectroscopy (EDX) and cathodoluminescence measurements allowing us to probe the elemental composition at the nanoscale. Perovskite solar cells fabricated from CBD SnO 2 and slot-die-coated perovskite show power conversion efficiencies up to 19.2%. Furthermore, mini-modules with an aperture area of 40 cm 2 demonstrate efficiencies of 17% (18.1% on active area).

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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.

Organic-inorganic hybrid perovskites are promising materials for thin-film solar cell technology due to their high power conversion efficiencies (PCEs) and solution process ability. [1] The best performing perovskite materials so far are relying on iodide-based compositions (such like CH 3 NH 3 PbI 3 and HC(NH 2 ) 2 PbI 3 ) or mixed iodide/bromide solutions leading to an optical bandgap in the range of 1.5-1.6 eV, not far from the theoretical optimum bandgap value that ranges between 1.2 and 1.4 eV for ideal solar cell. [2] Pure bromide-based compositions entail a wider optical bandgap transition and hence penalize the achievement of high PCE. [3,4] Nevertheless, the development of these bromide systems is very attractive due to the improved visible transparency and the higher open-circuit voltage values [5] that make them a potential candidate for electrochemical applications, [6] building integration photovoltaics (BIPVs), [7] and all-perovskite tandem solar cells. [8] Furthermore, their high photoluminescence (PL) quantum efficiencies attract huge interest for their integration as new emitters for light-emitting diodes (LEDs). [9,10] There have been several efforts to develop the CH 3 NH 3 PbBr 3based solar cells technology [5,11] leading so far to a record PCE of 10.4% on opaque devices. [4] One crucial issue to address in these systems is the large internal energy losses that manifest in the large difference (exceeding 0.6 V) between the optical bandgap and the open-circuit voltage measured under illumination. [12] This voltage loss is mainly ascribed to both the nonradiative