Graphoepitaxy of Large Scale, Highly Ordered CsPbBr₃ Nanowire Array on Muscovite Mica (001) Driven by Surface Reconstructed Grooves

Abstract Muscovite mica is a widely used van der Waals epitaxial substrate for growing high‐quality low‐dimensional crystals owing to its nondangling surface. However, there is a recent debate on the surface atomic arrangement, especially the lattice symmetry, of the cleaved muscovite (001), which is not only crucial for the crystal heteroepitaxy dynamics on the substrate, but also fundamental to optoelectronic devices based on few‐layered muscovite. Herein, the surface reconstruction of the cleaved muscovite (001) is investigated by using high‐resolution atomic force microscopy, which reveals that the removal of interlayer potassium induces a distortion to aluminosilicate tetrahedra by depressing the connecting oxygen, breaking the intrinsic quasi‐hexagonal symmetry and resulting in bunched grooves along the [100] direction. These grooves enable vapor‐phase graphoepitaxy of millimeter‐scale, unidirectional single‐crystalline CsPbBr₃ nanowire arrays without inducing unfavorable structural defects. Optical spectroscopy studies demonstrate their high optical quality and potential for anisotropic optoelectronic applications. These results further the understanding of epitaxial dynamics of muscovite (001), promote muscovite a powerful graphoepitaxy platform for anisotropic nanostructures, and provide insights into the development of few‐layered muscovite optoelectronic/proton devices.