Photoluminescent-dielectric duple switch in a perovskite-type high-temperature phase transition compound:...

A bistable optical-electrical duple switch belongs to a class of highly satisfying intelligent materials that can transform optical and electrical responses simultaneously in one device. A perovskite-type high-temperature phase transition compound with one-dimensional chain-like crystal structure, ([(CH₃)₃PCH₂OCH₃][PbBr₃], 1), displays remarkable bistable photoluminescent-dielectric duple switching behaviors. The noteworthy order-disorder transition of the phosphonium cation and the motions of anions contribute to the phase transition, leading to the space group P2₁/c at a low temperature phase to C2/c at a high temperature phase. 1 exhibits a prominent step-like dielectric anomaly at 401.0 K and demonstrates novel optical properties with a band gap of 3.54 eV. The photoluminescence intensity suddenly declines from 398 K to 408 K, which may be attributed to the occurrence of phase transition. The electron cloud distributions of the frontier orbital in compound 1 have been calculated using a DFT program.