A Thermoresponsive Lead‐Free Organic‐Inorganic Hybrid Perovskite as a Dielectric Switch

Abstract Thermochromic perovskites, renowned for their tunable bandgap, high absorption coefficient, and reversible color changes, emerge as promising candidates for applications in smart windows. These advancements not only have the potential to enhance occupant comfort but also contribute significantly to reducing energy consumption in buildings. Here, we present a two‐dimensional lead‐free organic‐inorganic hybrid perovskite [Cyclobutylammonium] 2 CuCl 4 which shows phase transitions from C 2/ c to P 2 1 / c to P 2 1 / c space group at 319.5 K and 348.8 K, respectively. Accompanying these transitions is a fascinating, reversible thermochromic behavior that is dependent on the phase structure. This behavior manifests as a vibrant sequence transitioning from yellow to brown and finally to a slightly dark brown. Most importantly, the demonstrated ability to switch stably between high and low dielectric states indicates the enormous potential of this material as a dielectric switch. This non‐toxic thermoresponsive perovskite, characterized by its appropriate transition temperatures, reversible phase structure‐dependent thermochromism, and stable dielectric switching behavior, is expected to generate significant interest within the fields of thermoresponsive and dielectric switching materials. The integration of these features not only positions this perovskite as a noteworthy subject of scientific inquiry but also opens avenues for practical applications in diverse fields.