# Methylammonium lead(II) iodide perovskites in bulk form

I am trying to obtain $$\ce{(MA)PbI3}$$ as a bulk powder using lead(II) iodide and methylammonium iodide as precursors.

I have not yet tried simply mixing the two in methanol/ethanol and removing the solvent in a rotavap, but this will simply result in a mixed salt with very little actual perovskite crystals if I am not mistaken.

So, how could I obtain $$\ce{(MA)PbI3}$$ in the highest purity possible using lead iodide and methylammonium iodide?

## 1 Answer

Procedure from the paper by Xie et al. [1] (Powder XRD didn't reveal any other impurity phases in the bulk samples):

Synthesis of $$\ce{CH3NH3PbI3}$$. The as-prepared $$\ce{CH3NH3I}$$ and $$\ce{PbI2}$$ (Sigma-Aldrich, 5N) were mixed in stoichiometric ratio and dissolved in γ-butyrolactone (Sigma-Aldrich), and then a 40wt% solution was formed. The solvent of as-prepared solution was evaporated in an oven at 60 °C for 2 days and $$\ce{CH3NH3PbI3}$$ precipitate was collected.

Similar approach has been utilized by Yamada et al. [2] for the synthesis of monocrystalline samples. From the SI:

### Sample Preparation

$$\ce{CH3NH3PbI3}$$ $$(\ce{MAPbI3})$$ single crystals were prepared from γ-butyrolactone solution at 100 °C. Purified lead iodide (2.73 g, 5.92 mmol) and methylammonium iodide (0.93 g, 5.84 mmol) were dissolved in dry γ-butyrolactone (4.8 mL) at 60 °C by stirring. The resulting solution was poured into a screw-cap vial which was placed on a hot plate at 100 °C for three days to produce a single crystal with dimensions of around 5 mm x 5 mm x 5 mm. We obtained a clean surface by cleaving the single crystal with thin knife under an Ar atmosphere before being used for the measurements. The experiments were conducted in an Ar atmosphere. We confirmed that the same results could be obtained with multiple samples that were cleaved and kept in Ar atmosphere.

Alternative method by Hoke et al. [3]; from the SI:

Crystals of $$\ce{(MA)PbBr3}$$ (orange, rhombic dodecahedra) were first grown by combining stoichiometric ratios of $$\ce{PbBr2}$$ and $$\ce{(MA)Br}$$ in concentrated (9 M) hydrobromic acid. Diffusion of acetone into this solution afforded crystals within 2 days, which were filtered and dried under reduced pressure.

It appears that methods described in [1] and [2] are based on the preparation of the solution of $$\ce{MAPbI3}$$ for the thin film deposition on $$\ce{TiO2}$$ layer, which was published earlier by Noh et al. [4] (SI).

### References

1. Xie, J.; Liu, Y.; Liu, J.; Lei, L.; Gao, Q.; Li, J.; Yang, S. Study on the Correlations between the Structure and Photoelectric Properties of $$\ce{CH3NH3PbI3}$$ Perovskite Light-Harvesting Material. Journal of Power Sources 2015, 285, 349–353. https://doi.org/10/f7c87m.
2. Yamada, Y.; Yamada, T.; Phuong, L. Q.; Maruyama, N.; Nishimura, H.; Wakamiya, A.; Murata, Y.; Kanemitsu, Y. Dynamic Optical Properties of $$\ce{CH3NH3PbI3}$$ Single Crystals As Revealed by One- and Two-Photon Excited Photoluminescence Measurements. J. Am. Chem. Soc. 2015, 137 (33), 10456–10459. https://doi.org/10/f7p5s9.
3. Hoke, E. T.; Slotcavage, D. J.; Dohner, E. R.; Bowring, A. R.; Karunadasa, H. I.; McGehee, M. D. Reversible Photo-Induced Trap Formation in Mixed-Halide Hybrid Perovskites for Photovoltaics. Chem. Sci. 2015, 6 (1), 613–617. https://doi.org/10/gc3g49.
4. Noh, J. H.; Im, S. H.; Heo, J. H.; Mandal, T. N.; Seok, S. I. Chemical Management for Colorful, Efficient, and Stable Inorganic–Organic Hybrid Nanostructured Solar Cells. Nano Lett. 2013, 13 (4), 1764–1769. https://doi.org/10/gc3g8w.