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- 2), and red-emissive β-[DHEP]SbCl 5 (3), by a dynamic phononengineering 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−on I −on II −off switching is realized in metal halide hybrids for the first time, including the off−on I (yellow), colortunable on I −on II (yellow-red), and on II −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.

Two new zero-dimensional hybrid indium halides of [H2DMP]2InX7·2H2O (X = Cl, Br) display intrinsic broadband yellow-orange light emissions with the highest quantum yield of 58.53%, which exceeds those of all previously reported 0D indium halides.

Intelligent stimuli-responsive fluorescence materials are extremely pivotal for fabricating luminescent turn-on switching in solid-state photonic integration technology, but it remains a challenging objective for typical 3-dimensional (3D) perovskite nanocrystals. Herein, by fine-tuning the accumulation modes of metal halide components to dynamically control the carrier characteristics, a novel triple-mode photoluminescence (PL) switching was realized in 0D metal halide through stepwise single-crystal to single-crystal (SC-SC) transformation. Specifically, a family of 0D hybrid antimony halides was designed to exhibit three distinct types of PL performance including nonluminescent [Ph 3 EtP] 2 Sb 2 Cl 8 ( 1 ), yellow-emissive [Ph 3 EtP] 2 SbCl 5 ·EtOH ( 2 ), and red-emissive [Ph 3 EtP] 2 SbCl 5 ( 3 ). Upon stimulus of ethanol, 1 was successfully converted to 2 through SC-SC transformation with enhanced PL quantum yield from ~0% to 91.50% acting as “turn-on” luminescent switching. Meanwhile, reversible SC-SC and luminescence transformation between 2 and 3 can be also achieved in the ethanol impregnation–heating process as luminescence vapochromism switching. As a consequence, a new triple-model turn-on and color-adjustable luminescent switching of off–on I –on II was realized in 0D hybrid halides. Simultaneously, wide advanced applications were also achieved in anti-counterfeiting, information security, and optical logic gates. This novel photon engineering strategy is expected to deepen the understanding of dynamic PL switching mechanism and guide development of new smart luminescence materials in cutting-edge optical switchable device.

Recently, zero‐dimensional (0D) hybrid metal halides have attracted intensive attention with wide applications in solid‐state lighting and display diodes. Herein, by using a facile wet‐chemistry method, we prepared one new 0D hybrid antimony halide of [HMHQ]2SbCl5 ⋅ 2H2O (MHQ=2‐methyl‐8‐hydroxyquinoline) based on the discrete [SbCl5]2− unit. Remarkably, the bulk crystals of [HMHQ]2SbCl5 ⋅ 2H2O exhibit strong cyan light emission with a promising photoluminescence quantum yield (PLQY) of 18.92%. Systematical studies disclose that the cyan emission is mainly derived from the radiative recombination within conjugated organic cation. Benefiting from the promising luminescent performance, this 0D antimony halide can be utilized as an excellent down‐conversion light emitting luminescent material to assemble white light‐emitting diodes with high color rendering index (CRI) of 90.2.