Near-room-temperature Tunable Dielectric Response Induced By Dual ...

Near-room-temperature tunable dielectric response induced by dual phase transitions in a lead-free hybrid: (C3H8N)2SbBr5†

Maofan Li,ab Bing Teng,*a Shiguo Han,b Tao Yang,ab Yaobin Li,b Yi Liu,b Xinyuan Zhang,b Xitao Liu, b Junhua Luo b and Zhihua Sun *b Author affiliations

* Corresponding authors

a College of Physics, Qingdao University, Qingdao, P. R. China E-mail: [email protected]

b State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, P. R. China E-mail: [email protected]

Abstract

Organic–inorganic hybrid materials, which exhibit structural diversity and rich physical properties, have shown great potential as basic device elements in the optoelectronic field. Herein, we report a new lead-free organic–inorganic hybrid compound, [C3H8N]2SbBr5 (1, where C3H8N+ is the cyclopropylammonium cation), which demonstrates tunable dielectric responses near room temperature, derived from its two successive structural phase transitions at the vicinity of T1 = 290 K and T2 = 315 K, respectively. That is, its dielectric constants change from high-dielectric (above T2), moderate-dielectric (between T2 and T1) and low-dielectric states (below T1). Such dielectric behaviors coincide well with a series of reversible thermal peaks in the DSC curve. Further structural analyses reveal that the order–disorder of organic cationic moieties accounts for the phase transition at T2, while the change of the molecular configuration provides the driving force to the phase transition at T1. Such phase transition behaviours differ from those of the majority of previously reported dielectric phase transition materials. Moreover, theoretical calculation of the electronic band structure of 1 reveals the direct feature with a band-gap value of ∼2.36 eV. This work affords broader design flexibility for the future exploration of electrically-ordered materials in the organic–inorganic hybrid family.

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