High Anisotropy in Tubular Layered Exfoliated KP₁₅

Two-dimensional (2D) materials with high anisotropic properties, such as black phosphorus and ReS₂, show amazing potential for applications in future nanoelectronic and optoelectronic devices. However, degradation of black phosphorus under ambient conditions and the expensiveness of Re block their application. In this study, another layered material, KP₁₅, that has highly anisotropic properties was successfully prepared. The detailed crystal structure and electron-density distribution calculation reveal that KP₁₅ exhibits an anisotropic layered structure with two rows of P tubes connected by K atoms that are antiparallel in a single layer. Outstanding chemical stability, angular dependence of the Raman response, excitation, and exciton emission at room temperature have been found in exfoliated KP₁₅ nanoribbons. Importantly, the exciton emission at room temperature suggests the existence of a large exciton binding energy. Our results indicate that, because this layered material, KP₁₅, has high anisotropic properties and ultrachemical stability and is derived from abundant raw materials, it has great potential for applications in optoelectronic devices.