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The microstructure of solid coatings produced by solution processing is highly dependent on the coupling between growth, solute diffusion, and solvent evaporation. Here, a quasi-2D numerical model coupling drying and solidification is used to predict the transient lateral growth of two adjacent nuclei growing toward each other. Lateral gradients of the solute and solvent influence the evolution of film thickness and solid growth rate. The important process parameters and solvent properties are captured by the dimensionless Peclet number (Pe) and the Biot number (Bi), modified by an aspect ratio defined by the film thickness and distance between nuclei. By variation of Pe and Bi, the evaporation dynamics and aspect ratio are shown to largely determine the coating quality. These findings are applied to drying thin films of crystallizing halide perovskites, demonstrating a convenient process map for capturing the relationship between the modified Bi and well defined coating regimes, which may be generalized for any solution processed thin film coating systems. 

This paper presents estimations for life cycle energy demand, human toxicity, and climate change of industrial-scale production of A-site cation precursor chemicals that may be used in production of perovskite solar cells. We employed process scale-up concepts, updated data sources and industry-relevant process modelling assumptions to build commercially relevant life cycle inventories (LCIs) for each of the perovskite precursors. Life cycle assessment (LCA) was applied to characterize and compare the resulting life cycle impacts and comparisons were made with other module components. The main finding of this work is that precursor impacts are similar to each other and about 1,000 times less than solar glass. Therefore, selection of perovskite compositions for commercialization should be driven solely by efficiency and stability rather than environmental concerns.