Reversible Triple-Mode Switching in Photoluminescence from 0D Hybrid Antimony Halides

Hybrid metal halides are an emerging class of highly efficient photoluminescent (PL) materials. However, very few of them show reversible on–off PL switching under external stimuli and have the potential to perform as next-generation intelligent materials with applications in cutting-edge photoelectric devices. Herein, we report single crystal-to-single crystal (SC–SC) structural and PL transitions among three 0D hybrid antimony halides, namely, nonemissive α-[DHEP]SbCl5 (1), yellow-emissive β-[DHEP]SbCl5·2H2O (2), and red-emissive β-[DHEP]SbCl5 (3), by a dynamic phonon-engineering strategy. The reversible SC–SC transformation between 1 and 2 is triggered by acetone or methanol, affording the reversible PL on–off switching. The transition between yellow-emissive and red-emissive solids is achieved by the reversible SC–SC transformation between 2 and 3 through the process of removal/adsorption of guest water molecules. Meanwhile, the 3 to 1 transition is performed by the introduction of methanol, which is accompanied by the quenching of red emission. Therefore, a triple-mode reversible PL off–onI–onII–off switching is realized in metal halide hybrids for the first time, including the off–onI (yellow), color-tunable onI–onII (yellow-red), and onII–off (red) modes. More importantly, the reversible PL switching in 0D hybrid antimony halides make them suitable for successful applications in the protection and anti-counterfeiting of confidential information as well as in optical logic gates.