Single Crystallization of Cs4PbBr6 Perovskite from Supersaturated Organic Solutions Optimized Through Solubility Studies

Satoshi Watanabe; Taiki Hayashida; Masaru Iwai; Yusuke Inomata; Masashi Kunitake; Tetsuya Kida

doi:10.1021/acsomega.2c06945

Single Crystallization of Cs₄PbBr₆ Perovskite from Supersaturated Organic Solutions Optimized Through Solubility Studies

ACS Omega. 2023 Jan 6;8(2):2455-2461. doi: 10.1021/acsomega.2c06945. eCollection 2023 Jan 17.

Authors

Satoshi Watanabe¹, Taiki Hayashida¹, Masaru Iwai¹, Yusuke Inomata¹, Masashi Kunitake², Tetsuya Kida²

Affiliations

¹ Faculty of Advanced Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto City, Kumamoto 860-8555, Japan.
² Institute of Industrial Nanomaterials, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto City, Kumamoto 860-8555, Japan.

Abstract

We demonstrate the fabrication of millimeter-sized single crystals of 0D-Cs₄PbBr₆ grown in a supersaturated solution consisting of organic solvents without HBr (aq). One of the precursors, CsBr, was dissolved in ethylene glycol (EG) mixed with dimethyl sulfoxide, which is a good solvent for the other precursor, PbBr₂. At a solvent ratio of 20 vol % EG, the solubility of cesium bromide decreased and the title compound, Cs₄PbBr₆, was selectively formed, whereas, with an EG ratio of 80 vol %, 3D-CsPbBr₃ was formed. A phase diagram (solubility curve) of Cs₄PbBr₆ in the mixed solvent containing 20 vol % EG was obtained by visually observing dissolution and crystal precipitation while changing the temperature. Because the solubility was proportional to the temperature, the solubility curve demonstrated an upper critical solution phenomenon. The solubility near the boiling point of the solution (150 °C) was approximately 0.14 M. A single crystal of Cs₄PbBr₆ was formed by growing a seed crystal in a supersaturated solution on the low-temperature side of the solubility curve. X-ray analysis established the crystal structure; a fluorescence emission at 520 nm with a full width at half maximum of 20 nm confirms the composition of the single crystal to be Cs₄PbBr₆.