Halogen‐Modulated Reversible Phase Transition in Organic‐Inorganic Hybrid Perovskites

The tunable structure, abundant raw materials, and ease of preparation have made molecular dielectric crystals popular for use in device design. In spite of this, some known molecular switching materials have a low phase transition temperature and a low dielectric constant, which limit their applications. Therefore, designing and synthesizing molecular‐based phase transition compounds with high phase transition temperature and superior properties is especially important. In this work, we use 3‐chloropropan‐1‐ammonium hydrochloride and SbCl3/SbBr3 inorganic salts as building blocks to synthesize compounds (CPA)2(BPA)2Sb2Br10 (1) (CPA=3‐chloropropan‐1‐ammonium, BPA=3‐bromopropan‐1‐ammonium) and (CPA)2Sb2Cl8 (2). Compound 1 has a high phase transition temperature (407.45 K). Dielectric measurements and differential scanning calorimetry (DSC) confirm the structural phase transition in compound 1, and no fatigue decay is observed after several dielectric cycles. In addition, compounds 1 and 2 possess semiconductor properties. The findings of this study provide new directions for the design and application of multifunctional molecular dielectric materials. Herein, we have successfully synthesized two organic‐inorganic hybrids (CPA)2(BPA)2Sb2Br10 (1) and (CPA)2Sb2Cl8 (2) (CPA=3‐chloropropan‐1‐ammonium, BPA=3‐bromopropan‐1‐ammonium). In addition, compound 1 possesses good dielectric properties. By studying their optical properties, we found that two compounds belong to indirect band gap semiconductors. Theoretical calculations were also performed to better understand the electronic structures of these two compounds.