Fabrication of CH₃NH₃PbBr₃-Based Perovskite Single-Crystal Arrays by Spin-Coating Method Using Hydrophobic Patterned Substrate

A simple and low-cost fabrication technique is proposed for CH₃NH₃PbBr₃-based perovskite single-crystal arrays by combining spin coating and a hydrophobic/hydrophilic patterned substrate. By optimizing the substrate surface treatment, the mixing ratio of the precursor solution, and the spin conditions, the precursor solution is uniformly aligned on the hydrophilic area, and the perovskite single crystal is precipitated at the center of the pattern area. The average lateral diameter of the precipitated plate-like crystals is controlled from 5 to 30 μm by changing the precursor concentration. The emission color of the precipitated crystals varies in the whole visible light region from violet (404 nm) to red (776 nm) by controlling the halogen composition of CH₃NH₃PbBr_3–nX_n (X = Cl, I) crystals via optimization of the solvent composition.