[C6H14N]PbI3: a one-dimensional perovskite-like order-disorder phase transition material with semiconducting and switchable dielectric attributes

An organic-inorganic semiconducting compound of 1-methylpiperidinium triiodoplumbate(ii) (MPIP), adopting a one-dimensional ABX(3) perovskite-like structure, has been synthesized. It is notable that MPIP undergoes a structural phase transition (SPT) at T-c similar or equal to 202 K, as confirmed by DSC and C-p analyses. Strikingly, MPIP exhibits remarkable switchable dielectric responses; that is, the distinct step-like anomalies in the vicinity of T-c. The switching between high-dielectric and low-dielectric states makes MPIP a potential switchable dielectric material. Single-crystal structural analysis reveals that the most distinct difference between its high-temperature phase (above T-c) and low-temperature phase (below T-c) is the order-disorder transformation of a 1-methylpiperidinium cation, which accounts for its SPT and striking dielectric response. Besides this, MPIP shows semiconducting behaviour with an optical bandgap of similar to 2.48 eV, comparable to some other lead-iodide perovskites. The combination of semiconducting and dielectric attributes provides a new perspective for the design of hybrid perovskites as multifunctional materials.