Control of perovskite film crystallization and growth direction to target homogeneous monolithic structures
D. Zheng, F. Raffin, P. Volovitch, T. Pauporté
Nat. Commun. 2022, 13, 6655
https://www.nature.com/articles/s41467-022-34332-3
Contacts | daming.zheng@chimieparistech.psl.eu, thierry.pauporte@chimieparistech.psl.eu
Abstract | Getting performant organo-metal halide perovskite films for various applications remains challenging. Here, we show the behavior of solvent and perovskite elements for four different perovskites families and nine different initial precursor solution systems in the case of the most popular preparation process which includes an anti-solvent dripping-assisted spin coating of a precursor solution and a subsequent thermal annealing. We show how the initial solution composition affects, first, the film formed by spin coating and anti-solvent dripping and, second, the processes occurring upon thermal annealing, including crystal domain evolution and the grain growth mechan- ism. We propose a universal typology which distinguishes three types for the growth direction of perovskite crystals: downward (Type I), upward (Type II) and lateral (Type III). The latter results in large, monolithic grains and we show that this mode must be targeted for the preparation of efficient perovskite light absorber thin films of solar cells.
Sketch of process in spin-coating. Prolonging the spin-coating time or using an antisolvent accelerates the reverse movement of lead and sulfur to promote the formation of the perovskite phase
Sketch of process in Annealing. Using the GD-OES detection method, we obtained the growth models of the four perovskite film systems and realized the regulation of film growth by adding various additives. Take MAPI as example, without any additive, the film growth of MAPI is downward, After the addition of nanoparticles as additive, the film growth becomes lateral growth, which is the ideal direction for film growth.
