High-Frequency Switchable Dielectric Properties of a Molecule-Based Hybrid Perovskite in a Microwave Band

Dielectric switch materials are widely used in network communication, data storage, and industry control, among which molecule-based hybrid perovskites have aroused extensive interest due to simple fabrication, lightweight, mechanical flexibility, and phase transition characteristics. However, current research on molecular materials mainly focuses on low-frequency ranges (1 kHz to 1 MHz), with limited exploration of high-frequency switching, which represents a development trend of electronics. Herein, we have synthesized three molecular perovskites, NH(CH₃)₃CdCl₃, (CH₃)₄NCdCl₃, and [(CH₃)₃NCH₂Cl]CdCl₃ (TMCM-CdCl₃), and studied their phase transition and dielectric properties in ultrawide range from 1 kHz to 18 GHz. They undergo phase transitions at 341, 374, 402, and 400 K, respectively. Notably, TMCM-CdCl₃ exhibited distinct dielectric anomalies in the whole studied frequency range, especially high-frequency dielectric switching in 12-18 GHz. NH(CH₃)₃CdCl₃ and (CH₃)₄NCdCl₃ only possess dielectric switching or no anomalies in low frequency bands. Dielectric loss of TMCM-CdCl₃ exhibits step-like elevation across phase transition, which endows it with "on/off" switchable microwave attenuation capability (reflection loss of -42.4 dB and effective absorption bandwidth of 5.7 GHz in the on state) at a thickness of 1.6 mm. This work highlights the high-frequency dielectric switching of molecular hybrid perovskites and provides insights into functionality explorations of molecule-based materials.