Impact of Processing on Structural and Compositional Evolution in Mixed Metal Halide Perovskites during Film Formation. (15th July 2020)

• Record Type: Journal Article
• Authors: Abdelsamie, Maged; Xu, Junwei; Bruening, Karsten; Tassone, Christopher J.; Steinrück, Hans‐Georg; Toney, Michael F.
• Is Part Of: Advanced functional materials. Volume 30:Number 38(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-07-15
• Subjects: compositional evolution -- crystallization pathways -- in situ GIWAXS -- metal halide perovskites -- phase segregation; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.202001752
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: Understanding crystallization processes and their pathways in metal‐halide perovskites is of crucial importance as this strongly affects the film microstructure, its stability, and device performance. While many approaches are developed to control perovskite formation, the mechanisms of film formation are still poorly known. Using time‐resolved in situ grazing incidence wide‐angle X‐ray scattering, the film formation of perovskites is investigated with average stoichiometry Cs0.15 FA0.85 PbI3, where FA is formamidinium, using the popular antisolvent dropping and gas jet treatments and this is contrasted with untreated films. i) The crystallization pathways during spin coating, ii) the subsequent postdeposition thermal annealing, and iii) crystallization during blade coating are studied. The findings reveal that the formation of a nonperovskite FAPbI3 phase during spin coating is initially dominant regardless of the processing and that the processing treatment (e.g., antisolvent dropping, gas jet) has a significant impact on the as‐cast film structure and affects the phase evolution during subsequent thermal treatment. It is shown that blade coating can be used to overcome the nonperovskite phase formation via solvothermal direct crystallization of perovskite phase. This work shows how real‐time investigation of perovskite formation can help to establish processing–microstructure–functionality relationships. Abstract : An in‐depth insight into the mechanism of film formation of mixed‐perovskites is provided. This work identifies the evolution of composition and volume fraction of phases during film formation and compares the mechanisms of empirically adopted processing strategies such as applying antisolvent or N2 ‐jet during spin coating, subsequent thermal annealing, and blade coating.