A Multifunctional High‐Entropy Perovskite Ceramics with Enhanced Energy Storage and Photoluminescence Properties

High‐entropy perovskite ceramics have become a topic of interest due to their unique properties and compositional versatility. This study pioneers the development of multifunctional high‐entropy perovskite ceramics by incorporating the rare‐earth element samarium (Sm) into the (Bi 0.4 Na 0.2 K 0.2 Ba 0.2 )TiO 3 matrix. The introduction of Sm 3+ increases the configurational entropy and introduces photoluminescence activation centers. Our results show that (Bi 0.4− x Sm x Na 0.2 K 0.2 Ba 0.2 )TiO 3 ceramics with x ≤ 0.12 retain pure perovskite phase and exhibit enhanced dielectric relaxation properties. The presence of Sm 3+ ions disrupts the long‐range ferroelectric order, resulting in lower maximum polarization and remanent polarization. In particular, the ceramic sample with x = 0.08 exhibits exceptional energy storage and photoluminescence properties. It achieves a recoverable energy storage density of 1.64 J cm − 3 and an efficiency ( η ) of 79.2% under a low electric field of 180 kV cm −1 . These properties position the material as a promising candidate for applications in electro‐optical devices.