Zero-dimensional (0D) all-inorganic/organic-inorganic metal halides, as emerging luminescent materials, have attracted unparalleled interest from versatile perspectives due to their unique ...crystallographic/electronic structures with isolated building units and fascinating optical characteristics. However, significant challenges still exist for 0D metal halides, including their chemical molecular design, photoluminescence (PL) mechanism, PL modification and applications. In this review, we summarize the 0D metal halides through the classification of all-inorganic and organic-inorganic hybrid metal halides, and further emphasize the unique role of B-site cations with different electronic configurations in the PL process. Furthermore, the PL mechanisms focusing on the self-trapped excitons (STEs) model and PL regulation engineering are examined to explore their extraordinary PL properties and further reveal new application prospects. This review aims to provide in-depth insight into the structure-luminescence-application relationship of 0D metal halides and pave the way for the realization of next-generation high-performance luminescent materials.
This review provides in-depth insight into the structure-luminescence-application relationship of 0D all-inorganic/organic-inorganic hybrid metal halide luminescent materials.
Garnets have the general formula of A
3
B
2
C
3
O
12
and form a wide range of inorganic compounds, occurring both naturally (gemstones) and synthetically. Their physical and chemical properties are ...closely related to the structure and composition. In particular, Ce
3+
-doped garnet phosphors have a long history and are widely applied, ranging from flying spot cameras, lasers and phosphors in fluorescent tubes to more recent applications in white light LEDs, as afterglow materials and scintillators for medical imaging. Garnet phosphors are unique in their tunability of the luminescence properties through variations in the {A}, B and (C) cation sublattice. The flexibility in phosphor composition and the tunable luminescence properties rely on design and synthesis strategies for new garnet compositions with tailor-made luminescence properties. It is the aim of this review to discuss the variation in luminescence properties of Ce
3+
-doped garnet materials in relation to the applications. This review will provide insight into the relation between crystal chemistry and luminescence for the important class of Ce
3+
-doped garnet phosphors. It will summarize previous research on the structural design and optical properties of garnet phosphors and also discuss future research opportunities in this field.
Crystal chemistry, luminescence and applications of Ce
3+
-doped garnets are reviewed and the tuning of optical properties is explained
via
combined insights from experiments and theory.
Phosphor materials enable the optical frequency conversion to realize the full-color white emission light-emitting diodes (LEDs). So far much effort has been devoted to the design and discovery of ...novel LED phosphors for solid state lighting. In this review, firstly, we briefly describe several representative families of LED phosphors. Secondly, we propose the design methodology aimed at discovery of new phosphors with focus on the crystal structural considerations. Thirdly, we review the results of our work and other researchers on the recent advances in discovery and structural design of LED phosphors that exemplify the adopted strategies, including (1) design of the novel phosphors from the existed structural models, (2) discovery of novel phosphors from new crystal materials by doping and (3) structural modification of the known phosphors. The importance on the structure-property relations and recently reported methodologies involved in the crystal chemistry analysis for the discovery of LED phosphors, including mineral-inspired structural model design, exploratory crystal growth via single particle diagnostic approach, chemical unit cosubstitution, and so on, have been summarized in this review. We finally discuss the topics of structure-related active investigations and future opportunities for new and improved host materials for the color conversion applied in LEDs.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Luminescent metal halide materials with flexible crystallography/electronic structures and tunable emission have demonstrated broad application prospects in the visible light region. However, ...designing near‐infrared (NIR) light‐emitting metal halides remains a challenge. Here, an enlightening prototype is proposed to explore the high‐efficiency broadband NIR emission in metal halide systems by incorporating Sb3+ into the Cs2ZnCl4 matrix. Combined experimental analysis and density functional theory calculations reveal a modified self‐trapped excitons model to elaborate the NIR emission. The high photoluminescence quantum yield of 69.9% peaking at 745 nm and large full width at half maximum of 175 nm, along with excellent air/thermal stability, show the unique advantages of lead‐free metal halide Cs2ZnCl4:Sb3+ as the NIR light source. The substitution of Cl− by Br− further enables the red‐shift of emission peak from 745 to 823 nm. The NIR light‐emitting diode device based on Cs2ZnCl4:Sb3+ demonstrates potential as a non‐visible light source in night vision. This study puts forward an effective strategy to design the novel eco‐friendly and high‐efficiency NIR emissive materials and provides guidance for expanding the application scope of luminescent metal halides.
High‐efficiency broadband near‐infrared (NIR) emission in metal halide systems is realized by incorporating Sb3+ into the Cs2ZnCl4 matrix. The high photoluminescence quantum yield of 69.9% peaking at 745 nm and large full width at half maximum of 175 nm, along with excellent air/thermal stability, show the unique advantages of lead‐free metal halide Cs2ZnCl4:Sb3+ as the NIR light source.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Lead‐free halide perovskites have drawn wide attention as alternatives to their toxic and poorly stable lead‐based counterparts. Among them, double perovskites with Cs2AgInCl6 composition, often ...doped with various elements, have been in the spotlight owing to their intriguing optical properties, namely, self‐trapped exciton (STEs) emission and dopant‐induced photoluminescence. This interest has sparked different synthesis approaches towards both crystals and nanocrystals, and the exploration of many alloy compositions with mono‐ and trivalent cations other than Ag+ and In3+. In this Minireview we describe the recent developments on Cs2AgInCl6 bulk crystals and nanocrystals, their synthesis strategies, intrinsic optical properties, and tunable photoluminescence originating from different alloying and doping effects. We also discuss progress on computational studies aimed at understanding the thermodynamic stability, the role of defects, and the origin of photoluminescence in relation to the STEs and the direct band gap character.
Lead‐free halide perovskites such as the easily synthesized double perovskite Cs2AgInCl6 have generated great attention as promising alternatives to lead‐based counterparts. This Minireview takes a close look at Cs2AgInCl6 materials in the form of bulk crystals as well as nanocrystals in terms of doping engineering, photoluminescence modification, and fundamental theoretical understanding.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
A series of new luminescent emission-tunable phosphors Ca2Al3O6F:Ce3+,Tb3+ have been synthesized by a high temperature solid-state reaction. The UV–vis reflectance, photoluminescence emission and ...excitation spectra, the lifetime, and the effect of Tb3+ concentration are investigated in detail. The intense green emission is realized in the Ca2Al3O6F:0.08Ce3+,0.05Tb3+ phosphors on the basis of the highly efficient energy transfer from Ce3+ to Tb3+ with an efficiency of over 90%. The energy transfer mechanism from Ce3+ to Tb3+ in the Ca2Al3O6F host was ascribed to the exchange interactions, and the formation of the Ce–Ce clusters and Ce–Tb clusters should be the reason for the high energy transfer efficiency. The critical distance of the energy transfer has also been calculated by the concentration-quenching method. These results indicate that the Ca2Al3O6F:Ce3+,Tb3+ phosphors have potential applications as a near UV-convertible phosphor for white light-emitting diodes because of its broad excitation in the near-ultraviolet range and the efficient green emission light.
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IJS, KILJ, NUK, PNG, UL, UM
Single‐component materials with white‐light emission are ideal for lighting applications. However, it is very challenging to achieve white luminescence in single‐dopant activated solid phosphors. ...Herein, white NaLi3Si1−xO4:Eu2+ materials are designed via defect engineering and synthesized by reducing the Si content (0.15 ≤ x ≤ 0.25). Stochiometric NaLi3SiO4:Eu2+ exhibits a narrow‐band blue emission at 469 nm, ascribed to the 5d → 4f transition of Eu2+ at highly symmetric cuboid Na sites, while samples with Si content reduced by 15–25% display white emission with two peaks at 472 nm and 585 nm. The newly appeared broadband yellow peak arises from charge‐transfer transitions involving Eu2+ and nearby defects, as verified by an unusual bandwidth, a large Stokes shift, and a long decay time. A single‐component white light‐emitting diode device is fabricated by employing a white phosphor to demonstrate a color‐rendering index of 82.9. This result provides a new design strategy for single‐component white‐light materials with broad‐band defect‐induced charge‐transfer emission.
A single‐component white emitter is developed by introducing defect‐associated charge‐transfer emission in a NaLi3SiO4:Eu2+ phosphor via a facile composition modification strategy. An extra broadband yellow peak (585 nm) appears in addition to the narrow‐band blue emission (472 nm). A single‐component white light‐emitting diode with color‐rendering index of 82.9 is fabricated using the white phosphor.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Near-infrared luminescent materials exhibit unique photophysical properties that make them crucial components in photonic, optoelectronic and biological applications. As broadband near infrared ...phosphors activated by transition metal elements are already widely reported, there is a challenge for next-generation materials discovery by introducing rare earth activators with 4f-5d transition. Here, we report an unprecedented phosphor K
LuSi
O
:Eu
that gives an emission band centered at 740 nm with a full-width at half maximum of 160 nm upon 460 nm blue light excitation. Combined structural and spectral characterizations reveal a selective site occupation of divalent europium in LuO
and K2O
polyhedrons with small coordination numbers, leading to the unexpected near infrared emission. The fabricated phosphor-converted light-emitting diodes have great potential as a non-visible light source. Our work provides the design principle of near infrared emission in divalent europium-doped inorganic solid-state materials and could inspire future studies to further explore near-infrared light-emitting diodes.
Stable and efficient phosphor systems for white light-emitting diodes (LEDs) are highly important with respect to their application in solid-state lighting beyond the technical limitations of ...traditional lighting technologies. Therefore, inorganic solid-state conversion phosphors must be precisely selected and evaluated with regard to their special material properties and synergistic optical parameters. In this perspective, we present an overview of the recent developments of LED phosphors; firstly, general photoluminescence-controlling strategies for phosphors to match LED applications have been evaluated; secondly, state-of-the-art and emerging new LED phosphors have been demonstrated. Then, methodologies for the discovery of new LED phosphors by mineral-inspired prototype evolution and new phase construction, as well as combinatorial optimization screening, and the single-particle-diagnosis approach, have been analyzed and exemplified. Finally, future developments of LED phosphors have been proposed.
The emerging new solid-state LED phosphors and the methodologies for their development have been reviewed in this perspective.
Understanding the structure–property relationship of inorganic solids has emerged as a prevailing strategy to provide guidelines for predicting and designing desired functional materials. Keeping an ...eye on the mineral structure-chemical composition–property paradigm, such structure-related design methodologies toward new luminescence materials for light-emitting diodes (LEDs) applications have been proposed, extensively utilized, and demonstrated potentials herein. In this review, we summarized several important design principles in the discovery of new inorganic phosphors by the following aspects: (1) constructing or evolving new phases toward novel phosphors from the existing natural mineral prototypes, and several mineral models have been discussed and exemplified by some phosphors; (2) modifying mineral structures via different substitution strategies based on known phosphors to tune the photoluminescence; (3) tuning local structures toward unprecedented emissions, including the state-of-the-art narrow-band emission and the near-infrared emission. Lastly, we discussed some future challenges and opportunities for mineral structure-related investigations in the hopes of directing the discovery and development of the new phosphor materials for LEDs applications.
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IJS, KILJ, NUK, PNG, UL, UM
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