Mixing Halogens To Assemble an All-Inorganic Layered Perovskite with Warm White-Light Emission

Most of single-component white-light-emitting materials focus on organic-inorganic hybrid perovskites, metal-organic frameworks, as well as all-inorganic semiconductors. In this work, we successfully assembled an all-inorganic layered perovskite by mixing two halogens of distinct ionic radii, namely, Rb₂ CdCl₂ I₂ , which emits "warm" white light with a high color rendering index of 88. To date, Rb₂ CdCl₂ I₂ is the first single-component white-light-emitting material with an all-inorganic layered perovskite structure. Furthermore, Rb₂ CdCl₂ I₂ is thermally highly stable up to 575 K. A series of luminescence measurements show that the white-light emission arises from the lattice deformation, which are closely related to the [CdCl₄ I₂ ]^2- octahedra with high distortion from the distinct ionic radii of Cl and I. The first-principles calculations reveal that both the Cl and I components make significant contributions to the electronic band structures of Rb₂ CdCl₂ I₂ . These findings indicate that mixing halogens is an effective route to design and synthesize new single-component white-light-emitting materials.