Schematic of first, slot-die coating (SDC) inorganics a), a heating step (3 min @ 70°C) and second SDC organics b) using two respective velocitiesv1.1andv1.2with subsequent dynamic gas-assisted slot jet drying c) with drying velocityv2. Drying is performed with a thin oblique impinging slot jet dryer at height.HD, with a slot width of 50 m ejecting nitrogen with a gas flow rateu0e). Schematic of the novel, alternative drying system, comb nozzle (CN) drying method is shown in d). The drying conditions are precisely defined via a 20 x 20 cm2nozzle array pattern consisting of hexagon-shaped jets (gas outlets, red) surrounded by slits for the local removal of the drying air (gas inlets, blue). This methodology allows to precise control of drying rates via a height.HCN, a gas temperatureTCN, ejection of the GB inert atmosphere with an adjustable heat transfer coefficientCNf), the latter being a figure of merit for the solvent removal. The formation of the perovskite thin film during gas-assisted drying is optimized for both alternatives, resulting in visibly similar homogeneous, pinhole-free perovskite thin films shown in photographs g, h). Inhomogeneities due to accumulated solution by the gas backflow of the slot jet and edge effects are marked in Figure 1g (hatched in red and green, respectively). Microscopic morphological differences are discussed in section2.3.
