Coordinated Anionic Inorganic Module—An Efficient Approach Towards Highly Efficient Blue‐Emitting Copper Halide Ionic Hybrid Structures

Abstract

Copper halide based organic–inorganic hybrid semiconductors exhibit great potential as light‐emitting materials with excellent structural variety and optical tunability. Among them, copper halide hybrid molecular compounds with discrete inorganic modules are particularly interesting due to their high quantum efficiency. However, synthesizing highly efficient blue‐emitting molecular clusters remains challenging. Here, we report a novel and facile strategy for the design and synthesis of highly luminescent copper halide hybrid structures by fabricating coordinated anionic inorganic modules in these ionic species. By using this approach, a family of strongly blue‐emitting copper halide hybrid ionic structures has been prepared with high internal quantum yields up to 98 %. Strong luminescence from the combination of ionic and covalent bonds in these compounds make them ideal candidates as alternative, rare‐earth‐element free light‐emitting materials for possible use in optoelectronic devices.

Zero-Dimensional Hybrid Indium Halides with Efficient and Tunable White-Light Emissions

“…All of the PL emission profiles, maximum wavelengths, and lifetimes of organic salts are close to those of blue emissions of 0D indium halides, demonstrating that the original blue emissions in hybrid indium halides should originate from their organic components. On the contrary, the lower-energy broadband yellow-light emissions with larger Stokes shifts and wide fwhm’s can be ascribed to the radiative recombination of self-trapped excitons (STEs) due to the electron–phonon coupling effect in a soft crystal lattice, which has been reported in numerous low-dimensional hybrid perovskites. − To confirm this speculation, temperature-dependent PL emission spectra upon excitation with 280 nm UV light were carried out for PhPz-In as an example due to the highest emission efficiency (Figure b). With a decrease in temperature from 300 to 80 K, the lower-energy broadband yellow-light emissions do not split into multiple peaks, verifying the single-excited-state nature.…”

“…Compared with 1D and 2D hybrid lead perovskites, zero-dimensional (0D) hybrid halide perovskites feature more tunable chemical compositions based on fruitful “green” metal ions, including In 3+ , Sb 3+ , Bi 3+ , Sn 2+ , etc., which provide an excellent structural platform for developing more desirable luminescent properties. − Compared with the instabilities of Sn 2+ and Ge 2+ halides, nearly fixed emission spectral ranges of Sb 3+ -based perovskites, and low efficiencies of Bi 3+ phases, In 3+ -based perovskites are more desirable for down-converter phosphors because of their multiple advantages, including tunable light emission, nontoxicity, high emission efficiency, strong oxidation resistance ability, etc. Furthermore, the completely isolated metal halide clusters with a strong spatial and quantum confinement effect result in firmly confined bound excitons, which give rise to the largest exciton binding energy and an ultrahigh PLQY at room temperature. , However, a vast majority of 0D hybrid halides display lower-energy light emissions from the green to red spectral range rather than white-light emission. , This failing is mainly related to the severely suppressed higher-energy emission from FEs because almost all FEs are trapped to form lower-energy STEs owing to the negligible potential energy barrier between FEs and STEs .…”

Solution-Processable Copper Halide Based Hybrid Materials Consisting of Cationic Ligands with Different Coordination Modes

“…Both the valence band maximum (VBM) and conduction band minimum (CBM) of compounds 1 and 2 are primarily populated by the atomic states from the inorganic clusters, namely, Cu 3d and I 5p for VBM and Cu 4s, Cu 4p, and I 6s for CBM. These results clearly suggest the typical CC emission nature of compounds 1 and 2 , similar to previously reported AIO structures made of N-monoalkylated TEDs. ,, …”

“…Depending on the hybridization of the coordinative atoms, sp 3 for aliphatic binding sites or sp 2 for aromatic binding sites, the AIO compounds so formed may follow different emission mechanisms. Ligands with aliphatic binding sites [e.g., N-monoalkylated TEDs (triethylenediamines)] have gained attention as low-cost and efficient cationic ligands for the construction of AIO structures with high photoluminescence quantum yields (PLQYs) and good thermal stability. ,, However, due to the lack of ligand π* states to participate in the emissive transition and the relatively close Cu···Cu distance (<2.80 Å, twice the vdW radius of Cu atom), their photoluminescence is typically a cluster-centered (CC) emission. ,, Therefore, their emission energies are mainly determined by the inorganic modules with limited ligand effect, making it difficult to tune the emission color. On the other hand, ligands with aromatic binding sites generally afford AIO structures that follow a metal/halide-to-ligand charge transfer [(M+X)­LCT] emission mechanism, which allows the systematic regulation of emission energy by adjusting the lowest unoccupied molecular orbital (LUMO) energies of the ligands .…”

Copper Iodide Cluster Incorporated Luminescent Organic–Inorganic Hybrid Coating Exhibiting Both Corrosion Protection and Antibacterial Properties

“…Copper­(I) iodide hybrid molecular clusters with a variety of specific discrete inorganic modules have excellent luminescence properties. − Through the “bottom-up” method, small molecules with specific copper (I) iodide clusters can be used as precursors to controllably synthesize multidimensional hybrid structures with the identical inorganic cluster structures, and such multidimensional hybrid structures can typically maintain the luminescent properties of the precursors . In view of this, a luminescent OIHC material (c-PTES) has been synthesized by the incorporation of the emissive Cu 4 I 4 core into an extended network through Cu–P coordination bonds using phenyltriethoxysilane (PTES) as the coupling reagent (Figures a and S1).…”