Perovskite/Metal‐Based Hyperbolic Metamaterials: Tailoring the Permittivity Properties of Coexisting Anisotropies in the Visible Region

Abstract Hyperbolic metamaterials (HMMs) based on plasmonic metals and solution processable metal halide perovskites are realized and studied. By harnessing the flexibility and unique properties of perovskites it is possible to tailor and tune the dispersion properties of such HMMs in the visible band. In particular, an HMM exhibiting direct transition from type I to type II in the mid‐visible region is demonstrated for the first time. The wavelength of this transition can be controlled and tuned over the whole visible band by modifying the combination of the perovskite and the plasmonic constituents. HMMs with such characteristics exhibit intriguing properties such as supercollimation, which is highly attractive for applications in imaging, solar power harvesting, and light emitting devices.