Light‐Induced Dielectric Enhancement in a 2D Dion–Jacobson Type Perovskite Phase Transition Material

Abstract Stimuli‐responsive materials, showing bistable behaviors between two distinct states under external stimuli, can be potentially applied as basic components of modern electrical and electronic devices. 2D hybrid perovskites hold a promise to switch and tune dielectric bistability based on their solid‐state phase transitions. Here, strong dielectric enhancements are successfully actualized by virtue of light illumination in a Dion–Jacobson (DJ) type 2D hybrid perovskite, (HDA)(MA)₂Pb₃Br₁₀ (1, where HDA is 1,6‐hexanediammonium and MA is methylammonium). Upon heating, 1 exhibits an ordered–disordered phase transition ≈ 324 K (T_c), accompanying a transition from its low to high dielectric state. Strikingly, its light‐induced dielectric constant changes are greatly enhanced with a magnitude up to 250% near the T_c, superior to most traditional inorganic phase transition materials. This process closely relates to the photoexcited dielectric effect that is caused by the interband photo‐excitation. Benefitting from the stability of DJ‐type perovskite structure, the switching cycles of dielectric enhancement display operational stability with superior anti‐fatigue characteristics. As per the knowledge, the findings of this strong dielectric enhancement are unprecedented in the family of 2D DJ‐type hybrid perovskites, which will facilitate broad interest in exploiting new stimuli‐responsive materials to assemble high‐performance smart electronic devices.