Vapor deposition of metal halide perovskite thin films: Process control strategies to shape layer properties

Vapor-based processes are particularly promising to deposit the perovskite thin film absorber of solar cells. These deposition methods are up-scalable, involve a controlled solvent-free environment, have the ability to conformally coat rough substrates, involve soft, low-energy deposition conditions, are compatible with shadow masks for patterning, and are already widely deployed at the industrial level. Still, solar cells featuring layers processed with these methods have not yet reached the same performance as their solution-processed counterparts, in part, due the complexity of controlling the sublimation of the organic precursors. This Research Update will discuss the different vapor-based deposition processes that have been reported to deposit perovskite thin films and will discuss reaction chamber designs that provide an enhanced control over the deposition process. The second part of this Research Update will then link experimental observations regarding layer properties depending on process conditions to theoretical concepts describing the sublimation and condensation of precursors and the growth of the perovskite thin film.