High-Symmetry Structural Phase Transition Triggers a Triple Switch Based on Dielectric, Nonlinear Optics, and Photoluminescence

Organic–inorganic hybrids have attracted wide attention due to the advantages of a designable structure and adjustable function. Among these, phase-transition hybrids can exhibit a variety of properties such as switchable dielectric and optical properties due to their rich chemical adjustability, stable physical properties, and distinct structural features, thus forming stimuli-responsive multifunctional materials. However, how to achieve multifunctional coupling of hybrid materials is still a big challenge. Herein, we have successfully synthesized a phase-transition structure [FPEA]2CdCl4 (FPEA=3-fluorophenethylamine), which undergoes a first-order phase transition at a high temperature of 380.4 K. The phase transition stems from the ordered–disordered dynamic motions of protonated cations and slight distortion of the inorganic framework. Notably, the compound improves the reversible switching of both dielectric and nonlinear optical (NLO) responses. At the same time, [FPEA]2CdCl4 shows broadband luminescence with a photoluminescence quantum yield of 31.07%. The multiple responses exhibited tremendous vitality and wide scope for exploration in sensors, smart switches, light-emitting diodes, and nonlinear optical devices.