Codoped 2D All-Inorganic Halide Perovskite Cs3Cd2Cl7:Sb3+:Mn2+ with Ultralong Afterglow.

Herein, we synthesized a Sb3+/Mn2+-codoped 2D all-inorganic halide perovskite Cs3Cd2Cl7:Sb3+:Mn2+ with ultralong afterglow emission at 579 nm. High-quality sheet-like single crystals are obtained by solvent evaporation and have an average crystal size of about 100 µm. We also synthesized Sb3+ and Mn2+ single-doped crystals by the same method so as to better understand the photophysical mechanism of the long afterglow phenomenon of the double-doped crystals. Through the codoping of Sb3+ and Mn2+, energy transfer occurs between the self-trapped exciton (STE) energy level of Sb3+ and the 4T1-6A1 transition of Mn2+, resulting in a visible afterglow of over 10 s. It is revealed that the changes in afterglow properties originate from the introduction of doping elements. And then, photoluminescence (PL) decay spectra and temperature-dependent PL spectra were tested to further illustrate the mechanism. Finally, it is proved that the codoped crystal has excellent stability and can meet various needs. All of the results demonstrate the unique afterglow properties and provide new examples for the development of all-inorganic halide afterglow materials.

All-Inorganic Luminescent Ternary Cadmium Halide Cs7Cd3Br13 with Two Types of Cd-Centered Polyhedrons.

All-inorganic metal halides comprise a class of semiconductor material with a wide range of applications. In these materials, cadmium-related materials have excellent optical properties in the field of binary quantum dots. However, ternary cadmium halides have not attracted much attention until now. Here, we successfully synthesize a ternary all-inorganic cesium cadmium bromide, Cs7Cd3Br13, and obtained its acicular single crystals through a simple solvent evaporation method. Cadmium atoms are found to be coordinated with bromine atoms in two different polyhedrons including isolated [CdBr4]2- tetrahedrons and corner-shared [CdBr6]4- octahedral chains in the unit cells of Cs7Cd3Br13. Optical properties are then measured and the needlelike single crystals are found to have an orange emission at 630 nm upon 365 nm UV light with a photoluminescence quantum yield (PLQY) of 9.85%. The orange luminescence with large Stokes shift (255 nm) and broad full width at half-maximum (fwhm = 147 nm) is derived from self-trapped excitons, and it is further evidenced by temperature-variable photoluminescence spectra. The PL decay spectrum shows the lifetime of Cs7Cd3Br13 is 1.26 µs. Finally, DFT calculation reveals that Cs7Cd3Br13 has a direct band gap with a value of 3.09 eV.

Solely 3-Coordinated Organic-Inorganic Hybrid Copper(I) Halide: Hexagonal Channel Structure, Turn-On Response to Mechanical Force, Moisture, and Amine.

Herein, we report a novel organic-inorganic hybrid CuI halide PyCs3Cu2Br6 (Py: pyridinium), where pyridinium and cesium ions coexist. We successfully develop a novel strategy for fabricating turn-on responsive materials. PyCs3Cu2Br6 has a higher single-crystal symmetry (no. 191) than its all-inorganic counterpart Cs3Cu2Br5 (no. 62), and the incorporation of organic pyridinium varied the coordination environment of CuI. PyCs3Cu2Br6 formed a triangle planar structure with solely 3-coordinated CuI ions, which quenched its luminescence. However, PyCs3Cu2Br6 presented a hexagonal channel structure, which enabled it with turn-on response upon mechanical force, heat, moisture, and amine vapor. Such structure offered channels for active molecules to diffuse and interact with pyridiniums, leading to the stimuli-triggered phase change to highly emissive Cs3Cu2Br5. To our best knowledge, for the first time, we discover a novel 3-coordinated organic-inorganic hybrid CuI halide with turn-on response to external stimuli. We believe that our study will contribute to expanding the landscape of smart stimulus-responsive materials and lay the foundation for their wide applications.

A Red-Emitting Hybrid Manganese Halide Perovskite C5H5NOMnCl2·H2O Featuring One-Dimensional Octahedron Chains.

Herein, we successfully synthesized a new organic-inorganic hybrid manganese halide perovskite C5H5NOMnCl2·H2O, in which organic molecules, water molecules (through O atoms), and Cl atoms coordinate with Mn atoms to form deformed [MnO3Cl3] octahedrons. Then, octahedrons form a chain through edge sharing, resulting in a 1D-chain single crystal structure. The high-quality C5H5NOMnCl2·H2O single crystal prepared by a simple solvent evaporation method produced bright red emission at 656 nm attributed to the d-d transition of Mn2+. Also, it has a photoluminescence quantum yield (PLQY) of 24.2%. Photoluminescence excitation and absorption spectra were both featured with multiple bands and were in good agreement with the Mn2+ 3d energy levels. The photoluminescence decay spectrum showed an average lifetime of 0.466 ms, which further proves the d-d transition mechanism. The C5H5NOMnCl2·H2O single crystal had a direct band gap of 1.43 eV. Moreover, a red light LED with a CCT of 1857 K was obtained based on the C5H5NOMnCl2·H2O powder, indicating its promising application in red-emitting LED.

Excitation-Dependent Luminescence of 0D ((CH3)4N)2ZrCl6 across the Full Visible Region.

Herein, we report a novel hybrid organic-inorganic Zr(IV) metal halide ((CH3)4N)2ZrCl6, which demonstrates fascinating excitation-dependent luminescence across the full visible region. The single crystal of ((CH3)4N)2ZrCl6 showed an unexpected high degree of symmetry and formed a unique 0D structure with isolated [ZrCl6]2- octahedrons. Amazingly, three different emission groups emerged under changeable excitation light. The first emission group peaked at 462 nm with a ns lifetime and a µs lifetime, which is assigned to free-exciton fluorescence and thermally activated delayed fluorescence (TADF). The second group of emissions featured elaborate multipeak light-emitting components, which is ascribed to the d-d transitions of Zr(IV). The third emission group centered at 660 nm was attributed to the typical self-trapped exciton (STE) emission. To our best knowledge, this work for the first time reports a 0D organic-inorganic metal halide with distinctive excitation-dependent full-visible-spectrum luminescence via four different emission mechanisms.