Three-Dimensional Metal-Free Molecular Perovskite with a Thermally Induced Switchable Dielectric Response

Temperature-responsive
materials with switching physical properties
have been widely researched. Among them, the switchable dielectric
perovskite materials show potential applications in the electrical
and electronic industries and even the intelligence industries. However,
perovskite oxides and hybrid organic–inorganic perovskites,
as the most representative switchable dielectric materials, are limited
by bad biocompatibility. Herein, we report temperature-dielectric-responsive
metal-free perovskite (H2dabco)­(NH4)­[BF4]3 constructed by the strategy of substituting
the B site in the general formula ABX3 (doubly protonated
1,4-diazabicyclo[2.2.2]­octane = H2dabco). Meanwhile, structurally
similar hybrid material (H2dabco)­Rb­[BF4]3 was designed as a control. They exhibit similar phase-transition
characteristics and dielectric response behaviors around 333 K. More
interestingly, the ordered–disordered transformation of their
organic “spherical” cations (H2dabco) was
deemed to produce their phase transitions and dielectric response
switching. Given its ability to generate a dielectric response, (H2dabco)­(NH4)­[BF4]3 will show
the potential application of metal-free perovskite in a future thermal
sensing device.