Embedding Te(IV) into a Robust Sn(IV)-Based Metal Halide for Deep-Red Emission

Organic-inorganic hybrid Sn(IV)-based metal halides have received wide attention due to their excellent structural stability. However, realizing red-emitting Sn(IV)-based metal halides with high stability and efficient photoluminescence (PL) efficiency remains challenging. Here, a stable organic-inorganic Sn(IV)-based metal halide (C8H10O2N)2SnCl6 with a zero-dimensional (0D) structure has been obtained, which, however, displays poor PL properties due to the inert expression of Sn4+-4d10 electrons and the intrinsic indirect band gap feature. To address the above challenges, Te4+ with an active 5s2 lone pair is embedded into the lattice of (C8H10O2N)2SnCl6, and as a result, 5%Te4+-doped (C8H10O2N)2SnCl6 with a direct band gap exhibits a broadband deep-red emission (∼688 nm) with a high PL efficiency (∼53%). Experimental and calculated results reveal that the embedding of Te4+ can effectively regulate the band structure of (C8H10O2N)2SnCl6 to facilitate the transformation from an indirect to a direct band structure, thereby leading to efficient radiative recombination. Benefiting from the above merits, a high-efficiency white light-emitting diode (WLED) has been fabricated using Te4+-doped (C8H10O2N)2SnCl6 with an ultrahigh color rendering index (CRI) of up to 94.5, suggesting the great potential of this material for solid-state lighting. This work provides significant insight into the design of highly efficient red-emitting phosphors for organic-inorganic hybrid metal halides.

Organic-Inorganic Hybrid Perovskite-Like Indium Chloride with Strong Red Emission

Low-dimensional organic-inorganic hybrid metal halide materials have attracted widespread attention due to their excellent and tunable photoelectric properties. However, the low intrinsic photoluminescence quantum yields (PLQYs) limit their further applications in optoelectronic devices. Here, we report the synthesis of lead-free zero-dimensional hybrid organic-inorganic indium chloride crystals, (FA)3InCl6: xSb3+, with strong red-light emission through controlled Sb3+ doping. The optimal composition, (FA)3InCl6: 20.16% Sb3+, exhibits PLQY up to 30% and emits red broadband light centered at 690 nm. The photoluminescence enhancement of the doped samples was investigated by combining temperature-dependent and wavelength-dependent photoluminescence spectra, revealing the self-trapped exciton (STE) recombination process. The clear elucidation of the self-trapped exciton complexation process has provided a solid theoretical basis for the further optimization of the material properties, which is of great significance for the development of new red light-emitting materials. Far-red light-emitting phosphor-converted LED devices have been constructed with these materials and demonstrate stable and efficient red-light emission at various voltages, exhibiting superior photoluminescence stability. This study highlights the potential of Sb3+-doped metal halides to achieve tunable broadband emission and demonstrates the great potential of these metal halide single crystals for indoor plant lighting, infrared imaging, photodynamic therapy and wound healing.

Mixed 1D/0D Structures of Chiral Hybrid Lead Halides with an l-Nicotinium Spacer Exhibit Broadband Photoluminescence and Polarized Emission

Hybrid lead halide materials have been highly studied for optoelectronics, but their use with chiral organics in chiro-optoelectronics remains limited. Understanding the ability to impart chirality into bulk materials by incorporating a chiral precursor is of great interest due to unique optical properties directly arising from chirality such as circular dichroism, optical rotatory dispersion, and circularly polarized luminescence. Herein, we used protonated l-nicotine (L-n) (nicotinium cations) as a spacer and templated a variety of structures including a series of (L-n)3M4X14 (M = Sn, Pb; X = Cl, Br, I) that take space group P63 in which the lead halide regions template two distinct moieties, both a 1D chain motif and a 0D cluster motif. Hydrogen bonding of the L-n and lone pair expression of the metal play a significant role in structural templating. The materials exhibit large band gaps of 2.70, 3.41, and 3.71 eV for X = I, Br, and Cl, respectively. They also exhibit broadband emission with a large Stokes shift, where the emission can come from both the cluster and chain depending on the composition and excitation. Single crystals exhibit linearly polarized light emission with iodide composition, giving a high degree of polarization of 0.61, among the highest reported for 1D hybrid lead halide materials at room temperature. Solution-processed thin films show strong CD responses corresponding to the choice of organic cation, indicating potential for device investigations.

One-Dimensional Perovskite RbGeI3 with Large Optical Anisotropy

Inorganic halide perovskites have been regarded as potential candidates for nonlinear optical (NLO) materials due to their large bandgaps and second-harmonic generation (SHG) effects. If these crystals exhibit large optical anisotropy, their birefringent phase-matching ability will undergo enhancement. In this study, a one-dimensional (1D) halide perovskite, RbGeI3, was experimentally synthesized. Its [GeI3]∞1 double chains are parallelly arranged, resulting in a large structural anisotropy with a birefringence of 0.122@1064 nm, the largest one in reported NLO-active inorganic halide perovskites, as determined from first-principles calculations. Furthermore, a comprehensive characterization involving Raman spectroscopy, the optical absorption spectrum, and powder SHG measurement was conducted to assess its suitability for NLO applications.

New highly efficient phosphorescent manganese halides as green and blue emitters

Three new manganese compounds on 5-(pyridin-2-yl)-3-phenyl-1,2,4-triazole (L) basis (HL)4[MnBr4]2·H2O (1), (HL)2[MnCl4] (2) and [MnL2Cl2]·H2O (3) have been synthesized and characterized in terms of their structure, photoluminescence (PL), and electroluminescence (EL) properties. Compounds 1 and 2 exhibit bright green luminescence (λem ≈ 550 nm) with high quantum yields of 75.1 and 71.2%, and 3 emits unusual blue emission at 438 nm with a quantum yield of 43.9%. Analysis of the spectral properties of complexes 1 and 2 indicates that luminescence is determined by the transfer of excitation energy from the triazole cation to the manganese cation. Electroluminescent devices based on complexes 1 and 3 show high brightness values of 3033 and 5230 Cd m-2, respectively.

Naphthalenediimide-Based Hybrid Material with Eu-Substituted Polyoxometalate: Photochromism, Near-Infrared Photothermal Conversion, and C-3 Functionalization of Indoles

Designing and developing novel photochromic materials with additional functions such as photothermal conversion and photocatalysis are challenging but meaningful objectives. Crystalline naphthalenediimide (NDI)-based hybrids are an attractive class of multifunctional materials with fast-response photoinduced electron transfer and charge separation properties. They are promising photothermal conversion materials and photocatalysts. Herein, a novel hybrid material, EuPMo11O39(L)1.5(H2O)2]·DMA (EuMo-NDI) (L = N,N'-di(1-oxido-4-pyridyl)-1,4,5,8-naphthalenediimide), was prepared with a solvothermal method, integrating a photoactive NDI derivative and an Eu-substituted polyoxometalate. EuMo-NDI exhibits 0D structure with sensitive photochromic behavior under UV-vis light irradiation due to fast-response photoinduced electron transfer between its components. The colored EuMo-NDI sample demonstrated efficient near-infrared photothermal conversion due to the strong absorption of the photogenerated radical anion NDI•- and mixed valence heteropoly blue in the near-infrared region. Meanwhile, EuMo-NDI is easily excited in the presence of electron donors to form the radical species, which can activate inert O2 to superoxide radical O2•-. EuMo-NDI exhibited high photocatalytic activity for C-3 thiocyanation of indoles under mild conditions using white light as a driving force. This work provides an effective avenue to design novel photothermal conversion materials and photocatalysts using photochromic materials as platforms.

Chirality-Dependent Anisotropic Nonlinear Optical Effect in Low-Dimensional Hybrid Metal Halides

Low-dimensional hybrid metal halides (LDHMHs) have emerged as a highly promising class of functional materials for a wide range of optoelectronic applications. Their exceptional structural tunability, facilitated by the hybridization of metal halides with organic compounds, enables the formation of three-, two-, one-, or zero-dimensional structures. This flexibility in structural design also allows the incorporation of chirality into the crystalline lattice, giving rise to novel LDHMH materials that are capable of selectively interacting with the spin angular momentum of electrons and photons. Among the unique optoelectronic properties of LDHMHs, the focus of this concept article is their chiroptical nonlinear optical (NLO) effect. LDHMHs demonstrate a highly effective discrimination and generation of circularly polarized (CP) light in the NLO regime, particularly in the second harmonic generation (SHG) process, referred to as SHG-circular dichroism (SHG-CD) and CP-SHG. These anisotropic responses are several orders of magnitude larger than linear chiroptical responses, such as CD and CP luminescence; consequently, LDHMHs are expected to be promising candidates for future optical-information devices and encryption systems. This article introduces recently reported chiral LDHMH materials that exhibit excellent CP-dependent anisotropic SHG responses.

Pseudohalide Anions Driven Structural Modulation in Distorted Tetrahedral Manganese(II) Hybrids Toward Tunable Green-Red Emissions

Mn(II)-based halides have recently garnered significant interest as emerging luminescence materials for diverse photonic applications. Generally, Mn(II) hybrids with tetrahedral coordination show green emission, however, ones with octahedral coordination give red emission. Herein, we design the synthesis of tetrahedral Mn(II) pseudohalide hybrids, (RPh3P)2MnBrxNCS4-x (R=phenyl, pentyl or methyl; Ph3P=triphenylphosphine; x=1-3), achieved by gradually substituting bromides with pseudohalides (NCS-). Compared to the green-emitting A2MnBr4 (512 nm), the mixed hybrids exhibit significantly distorted [MnBrxNCS4-X] tetrahedra with high dipole moment, thus leading to the distinct Stokes shift energies and noticeable red shift emission in the range of 549-613 nm. Furthermore, the photoluminescence quantum yield (PLQY) of these hybrids correlates strongly with the pair correlation function of Mn(II) ions, specifically the Mn⋅⋅⋅Mn distance. These findings highlight the critical role of dipole moments in determining the emission properties and expand the luminescent family of Mn(II) pseudohalide hybrids.

Emerging 0D Hybrid Metal Halide Luminescent Glasses

0D hybrid metal halide (HMH) luminescent glasses have garnered significant attentions for its chemical diversity in optoelectronic applications and it also retains the skeleton connectivity and coordination mode of the crystalline counterparts while exhibiting various physics/chemistry characteristics distinct from the crystalline states. However, understanding of the glass-forming ability and the specific structural origins underpinning the luminescent properties of 0D HMH glasses remains elusive. In this review, it is started from the solid-liquid phase transition and thermodynamic analysis of 0D HMHs formed through melt-quenching, and summarize the current compounds capable of stably forming glassy phases via chemical structural design. The structural characterization methods are further discussed and highlight the exceptional transparency, specific luminescent properties, and glass crystallization behaviors. Moreover, the application prospects demonstrated by these 0D HMH glasses have been presented accordingly in X-ray detection and imaging, anti-counterfeiting, and information encryption. Finally, perspective is offered into the future development of this emerging family of 0D HMH glasses and their applications.

Unveiling Doping Kinetics in Cu(I) Metal Halides for Customized Luminescent Performance

Intentional doping plays a pivotal role in customizing metal halides' electronic and optical features. This work manipulates the incorporation and distribution of Mn2+ in Cu(I) halide by controlling the elemental steps involved in the growth-doping kinetics as well as investigates the localized lattice and electronic structures in different doping configurations. Complementary experimental and theoretical results demonstrate that a uniform and relatively high Mn2+ doping level can be achieved by a step-tailored strategy that encompasses reducing the growth rate of the halide matrix, enhancing the surface adsorption of Mn2+, and facilitating the incorporation of the dopants. The optimized doping configuration mitigates severe lattice distortion and decreases the non-radiative transition rate, resulting in explicit dual-band emission and an enhanced photoluminescence quantum yield. This work underscores an effective synthesis strategy to harness the full potential of Mn2+-doped metal halides beyond Cu(I)-based ones and also showcases a new working paradigm of separately controlling the doping procedures for obtaining metal halides with customized optical/optoelectronic properties.

Lantern-Shaped Structure Induced by Racemic Ligands in Red-Light-Emitting Metal Halide with Near 100 % Quantum Yield and Multiple-Stimulus Response

Organic-inorganic metal halides (OIMHs) have become a research hotspot in recent years due to their excellent luminescent properties and tunable emission wavelengths. However, the development of efficient red-light-emitting OIMHs remains a significant challenge. This work reports three Mn-based OIMHs derived from 1-methyl-1,2,3,4-tetrahydroisoquinoline hydrobromide: racemic one (Rac-TBM) and chiral ones (R-TBM and S-TBM). As a result of the synergism of chiral organic ligands inducing a unique lantern-shaped hybrid structure containing both tetrahedra and octahedra, Rac-TBM exhibits red-light emission with near-unity luminescence quantum yield. In comparison, the chiral counterparts R/S-TBM display strong green emission and circularly polarized luminescence (CPL) with a glum value up to ±2.5×10-2. Interestingly, a mixture of R- and S-TBM can transform into Rac-TBM, successfully achieving a sensitive and reversible switch between red light of octahedra and green light of tetrahedra under external stimuli. The outstanding luminescent properties allow Rac-TBM to be utilized not only for X-ray radioluminescence with a detection limit down to 46.29 nGys-1, but also for advanced information encryption systems to achieve leak-proof decryption.

Excitation-mode-selective emission through multiexcitonic states in a double perovskite single crystal

Low-dimensional lead-free metal halide perovskites are highly attractive for cutting-edge optoelectronic applications. Herein, we report a class of scandium-based double perovskite crystals comprising antimony dopants that can generate multiexcitonic emissions in the ultraviolet, blue, and yellow spectral regions. Owing to the zero-dimensional nature of the crystal lattice that minimizes energy crosstalk, different excitonic states in the crystals can be selectively excited by ultraviolet light, X-ray irradiation, and mechanical action, enabling dynamic control of steady/transient-state spectral features by modulating the excitation modes. Remarkably, the transparent crystal exhibits highly efficient white photoluminescence (quantum yield >97%), X-ray excited blue emission with long afterglow (duration >9 h), and high-brightness self-reproducible violet-blue mechanoluminescence. These findings reveal the exceptional capability of low-dimensional perovskite crystals for integrating various excitonic luminescence, offering exciting opportunities for multi-level data encryption and all-in-one authentication technologies.

Single-Component Coordination Polymers with Excitation Wavelength- and Temperature-Dependent Long Persistent Luminescence toward Multilevel Information Security

Metal-organic hybrid materials with long persistent luminescence (LPL) properties have attracted a lot of attention due to their enormous potential for applications in information encryption, anticounterfeiting, and other correlation fields. However, achieving multimodal luminescence in a single component remains a significant challenge. Herein, we report two two-dimensional LPL coordination polymers: {[Zn2(BA)2(BIMB)2]·2H2O}n (1) and {[Cd(BA)(BIMB)]·3H2O}n (2) (BIMB = 1,3-bis(imidazol-1-yl)benzene; BA = butanedioic acid). Their LPL colors can be adjusted by the excitation wavelength or temperature variation in a single-component coordination polymer, achieving multimode color adjustment from green to orange or blue to yellow. X-ray single-crystal diffraction analysis and theoretical calculations demonstrate that abundant intermolecular interactions, ligand-to-ligand charge transfer (LLCT) transitions, and heavy atom effects of the central metal can realize multicolor afterglow. This work provides a convenient strategy for new pattern multicolor LPL materials and may also inspire new ideas for advanced information encryption technologies.

Achieving Bright Luminescence and X-ray Scintillation in Zero-Dimensional Cesium Zinc Bromides by Cu+-Mn2+ Codoping

Zero-dimensional (0D) metal halides have emerged as excellent luminescent materials for optical and optoelectronic applications. Especially environmentally friendly ternary zinc halides have recently drawn increasing attention. Herein, we present the codoping of Cu+ and Mn2+ ions into 0D Cs2ZnBr4 single crystals (SCs), which show bright PL emission and high stability. Adjusting the Cu+/Mn2+ ratio can make the photoluminescence quantum yield (PLQY) exceed 90%, which is much higher than that of the single-ion doped sample. The efficient PL is determined by a combination of Cu+-Mn2+ competitive interaction, Cu+-Mn2+ energy transfer, and Cu+-Mn2+ synergistic passivation. More interestingly, the codoped sample shows a better scintillation performance with a low detection limit of 52 nGyair/s and a sensitive spatial resolution of 13.2 lp/mm. We further explore the promising applications of Cu+-Mn2+-codoped Cs2ZnBr4 SCs for anticounterfeiting and X-ray imaging. These results not only help to grasp the excited-state photophysical processes of 0D codoped metal halides but also provide a new way for the design and development of environmentally friendly luminescent materials.

Vacancy Effect on the Luminescent and Water Responsive Properties of Vacancy-Ordered Double Perovskite Derivatives

Vacancy-ordered perovskites and derivatives represent an important subclass of hybrid metal halides with promise in applications including light emitting devices and photovoltaics. Understanding the vacancy-property relationship is crucial for designing related task-specific materials, yet research in this field remains sporadic. For the first time, we use the Connolly surface to quantitatively calculate the volume of vacancy (V□, □=vacancy) in vacancy-ordered double perovskite derivatives (VDPDs). A relationship between void fraction and the structure, photoluminescent properties and humidity stability was established based on zero-dimensional (0-D) [N(alkyl)4]2Sb□Cl5□'-type VDPDs. Compared with the more commonly studied A2M(IV)X6□-type double perovskite (A=cation, M=metal ion, X=halide), [N(alkyl)4]2Sb□Cl5□' features double vacancy sites. Our results demonstrate an inverse relationship between the photoluminescent quantum yield and V□ in 0-D VDPDs. Additionally, structural transformation from A2SbCl5 to A3Sb2Cl9 was first reported, during which the novel 'gate-opening' gas adsorption phenomenon was observed in VDPDs for the first time, as evidenced by 'S'-shaped sorption isotherms for water vapor, indicating a cation-controlled water-vapor response behavior. A mixed-cation strategy was developed to modulate the humidity stability of VDPDs. Characterized by controllable water-responsive behavior and unique 'on-off-on' luminescent switching, A2M(III)□X5□'-type materials show great promise for multi-level information anti-counterfeiting applications.

Controllable Multi-Exciton Zero-Dimensional Antimony-Based Metal Halides for White-light Emission and β-Ray Detection

Self-trapped exciton (STE) emission, typified by antimony (Sb), with broadband characteristics, represents the next generation of materials for solid-state lighting and radiation detection. However, little is known about the multiexciton behavior of the Sb emission center. Here, we proposed a general approach for designing antimony-centered multi-exciton emitting materials through self-assembly. Benefitting from controllable multiexciton behavior, dual-band white light emission spanning the entire visible spectrum was achieved. Relying on the reduction of an effective atomic number brought by self-assembly, excellent scintillation response to β-rays was attained. This study offers unprecedented insight into hybrid single/triple STE emission and unveils new avenues for single-emitter white-light emission, as well as radiographic testing using low-risk β-rays as sources.

Exploring the effect of pressure on the crystal structure and caloric properties of the molecular ionic hybrid [(CH3)3NOH]2[CoCl4]

The hybrid metal halide [(CH3)3NOH]2CoCl4 exhibits a first-order phase transition at T ∼ 343 K. Its crystal structure and caloric properties respond significantly to moderate pressures (1-1000 bar), demonstrating potential for applications in emerging solid-state refrigeration technologies.

Tunable Blue-Light-Emitting Organic-Inorganic Zinc Halides with Thermally Activated Delayed Fluorescence and Room-Temperature Phosphorescence

Hybrid metal halides have received great interests in the field of solid-state lighting technologies due to their diverse structures and excellent emission properties. In this work, we report the synthesis and characterization of four blue-emitting zero-dimensional hybrid metal halides, namely, (2HP)2ZnCl2, (2HP)2ZnBr2, (2TP)2ZnCl2, and (2TP)2ZnBr2 (2HP = 2-hydroxypyridine, 2TP = pyridine-2-thiol). By changing the ligands and halides, a remarkable increase in the photoluminescence quantum yield of (2HP)2ZnCl2 (44.7%) compared to (2TP)2ZnBr2 (1.8%) is realized. The 2HP series features excitation-dependent emission characteristics, whereas the 2TP series does not due to the effect of a different organic ligand. Utilizing time-resolved and temperature-dependent photoluminescence spectroscopies, all four compounds exhibit both thermally activated delayed fluorescence and room-temperature phosphorescence properties. These materials have excellent ambient and thermal stabilities and are solution-processable. Our work shows the importance of carefully incorporating organic ligands with the appropriate inorganic metal center to achieve tunable emission properties.

Precise Modification of Organic Cations to Enhance the Moisture Stability and Luminescence Efficiency of Mn-Based Halides

Eco-friendly organic-inorganic hybrid metal halides (OIMHs) are widely recognized as promising candidates for next-generation semiconductor materials. However, achieving inherent moisture stability in OIMHs remains a significant challenge due to the highly hygroscopic nature of the halide structures. In response, a strategy to precisely modify the organic cation (18-ACE: 4,13-diaza-18-crown 6-ether) was developed by introducing hydrophobic benzyl groups into 18-ACE, forming a protective layer that enhances the moisture stability of the OIMHs. Specifically, benzyl groups were incorporated into 18-ACE to create 18-ACE-Bn, which was then used as an organic component to construct zero-dimensional Mn-based (18-ACE)MnBr4 and (18-ACE-Bn)MnBr4·H2O, exhibiting photoluminescence quantum yields (PLQYs) of 68.18% and 97.17%, respectively. Notably, (18-ACE-Bn)MnBr4·H2O demonstrates exceptional moisture stability compared to (18-ACE)MnBr4, retaining 97% of its initial PLQY even after 180 days of exposure to 70% relative humidity. Molecular dynamics and density functional theory calculations indicate that this superior stability is attributed to the terminal benzyl groups embedded within the inorganic framework, forming a compact structure with abundant weak interactions. Leveraging the unique spectral characteristics of (18-ACE-Bn)MnBr4·H2O, a high-performance WLED with a wide color gamut of 125.2% NTSC (National Television Standard Committee) was developed, highlighting its potential for backlight display applications.

Chiral Rare-Earth (Ce, Eu) Metal Halides with Bright Circularly Polarized Luminescence

Chiral metal halide materials are emerging chiroptical materials that are easy to synthesize and have a wide tunability. Rare-earth (RE) metals are desirable components to be incorporated in the hybrid regime; however, they are typically difficult to handle for solution-based halide chemistry. Here, we report two new examples of chiral RE metal halides with Ce(III) and Eu(III) with chiral alkanolammonium cations (R/S-3-hydroxyquinuclidium). These compounds crystallize in the non-centrosymmetric space group R3, where their mirror-like symmetric circular dichroism (CD) and circularly polarized luminescence (CPL) further witness the chiral nature. The superior emission properties, including the high photoluminescence quantum yield of the Ce-based materials (84-90%) and Eu-based materials (27-29%), have led to distinct and sharp symmetrical CPL in the ultraviolet and visible regions, with dissymmetry factors (glum) of ∼2 × 10-3 and ∼4 × 10-3, respectively. This work has established and expanded the materials space for chiral RE metal halides and demonstrated their potential for chiroptical and spintronic applications.

Stable Long-Persistent Luminescence from Self-Activated CaSb2O6 Induced by Intrinsic Defects

Long-persistent luminescence (LPL) materials have attracted intensive attention due to their fascinating emission after excitation. However, current LPL materials typically depend on external doping to introduce traps or emitting centers, resulting in a complex synthesis and controllability. For the first time, we develop another category of undoped LPL materials based on antimonate CaSb2O6, which exhibits blue LPL for over 8000 s. Both experimental and theoretical evidence indicate that excitons are trapped by intrinsic oxygen vacancies. Then, they are detrapped and recombine through singlet and triplet emission of Sb3+ to form LPL. Moreover, CaSb2O6 maintains approximately 100% of its initial LPL performance and structural integrity even after being treated under 1000 °C, UV irradiation, and extreme conditions (pH = 1 or 13). This study highlights the significant potential of antimonates as robust and versatile luminescent materials.

Structural Design of Hybrid Manganese(II) Halides for High Quantum Efficiency and Specific Response to Methanol

Manganese(II) halides have been a new generation of optoelectronic materials due to their fascinating luminescent properties, however, lacking specific solvent-responsive analogues with high quantum efficiency. Herein, we prepared three single crystals, [Pr(MIm)2][MnBr4] ([Pr(MIm)2]2+ = 1,3-di(methylimidazolium)-propane, Compound 1), [Pr(EIm)2][MnBr4] ([Pr(EIm)2]2+ = 1,3-di(ethylimidazolium)-propane, Compound 2), and [Bu(MIm)2][MnBr4] ([Bu(MIm)2]2+ = 1,4-di(methylimidazolium)-butane, Compound 3), where different Bola-type cations were chosen as organic components to separate [MnBr4]2- tetrahedrons. All three compounds emitted bright green light with excellent quantum yields of 95.3, 80.0, and 96.2%, benefiting from the large Mn···Mn distance. More interestingly, Compound 3 showed a highly selective response to methanol in a series of tested organic solvents, with a rapid and reversible change in emission color from green to red. The single crystal of [Bu(MIm)2][MnBr4]·CH3OH with red emission proved that the luminescence switching was attributed to the adsorption of CH3OH molecules into the lattice space in the form of the O-H···Br hydrogen bonds. To our knowledge, for tetrahedrally coordinated Mn(II) species, the reversible emission color switching between green and red triggered by a solvent without the change of coordination number is achieved for the first time, providing promising applications for the specific detection of methanol.

Photoluminescence Enhancement of 0D Organic-Inorganic Metal Halides via Aggregation-Induced Emission and Halide Substitution

0D organic-inorganic metal halides (OIMHs) provide unprecedented versatility in structures and photoluminescence properties. Here, a series of bluish-white emissive 0D OIMHs, (TPE-TPP)2Sb2BrxCl8-x (x = 1.16 to 8), are prepared by assembling the 1-triphenylphosphonium-4-(1,2,2-triphenylethenyl)benzene cation (TPE-TPP)+ with antimony halides anions. Based on experimental characterizations and theoretical calculations, the emission of the 0D OIMHs are attributed to the fluorescence of the organic cations with aggregation-induced emission (AIE) properties. The 0D structure minimized the molecular motion and intermolecular interactions between (TPE-TPP)+ cations, effectively suppressing the non-radiative recombination processes. Consequently, the photoluminescence quantum efficiency (PLQE) of (TPE-TPP)2Sb2Br1.16Cl6.84 is significantly enhanced to 55.4% as compared to the organic salt (TPE-TPP)Br (20.5%). The PLQE of (TPE-TPP)2Sb2BrxCl8-x can also be readily manipulated by halide substitution, due to the competitive processes between non-radiative recombination on the inorganic moiety and the energy transfer from inorganic to organic. In addition, electrically driven light-emitting diodes (LEDs) are fabricated based on (TPE-TPP)2Sb2Br1.16Cl6.84 emitter, which exhibited bluish-white emission with a maximum external quantum efficiency (EQE) of 1.1% and luminance of 335 cd m-2. This is the first report of electrically driven LED based on 0D OIMH with bluish-white emission.

A core-shell model of polymetallic hybrid metal halides

Most polymetallic hybrid metal halides are assumed to show a homogenous distribution of the metal ions in the bulk. Herein, we demonstrate a core-shell model for the hybrid lead halide [(C6H18N3)2·Pb2Br10] (C6H18N3 = 2-(piperazin-1-yl)ethan-1-aminium) coated with a manganese bromide layer. This model can explain the different photoemission of this composite material, and provides new insights on the investigation of polymetallic low-dimensional organic metal halides.

Intense white-light emission of amorphous lead chloride trimers at high pressure

Developing efficient, single-phase white-light phosphors remains a formidable challenge in optoelectronics. Herein, high pressure initially induces trimeric contraction and distortion in (C9NH20)9(ZnCl4)2[Pb3Cl11], regulating the transition equilibrium of self-trapped excitons (STEs) with varied emission colors. Then, considerable structural distortion and destruction lead to intense white-light emission of an amorphous phase. A narrowed bandgap with promoted excitation efficiency, as well as strengthened electron-phonon coupling effect with increased binding energy of STEs, together result in the significant emission enhancement. This work provides valuable insights into white-light luminescent materials and offers new strategies for designing white-light-emitting devices.

White Light Emission in Zero-Dimensional Indium Hybrid with Hydrogen Bond

Low-dimensional organic-inorganic metal halides (OIMHs) have been explored as single-component white light emitters for applications in solid-state lighting. Herein, we report a zero-dimensional (0D) In-based OIMH (TMPDA)[InCl5(H2O)] (TMPDA = N,N,N',N'-tetramethyl-1,4-phenylenediamine), which crystallizes in the noncentrosymmetric P212121 space group and contains hydrogen bonds between the adjacent [InCl5(H2O)]2- octahedra in structure. It exhibits a large optical band gap (4.10 eV) and dual-band emission under UV light. Spectroscopic analysis and theoretical calculation indicate that the high (404 nm)- and low (513 nm)-energy emissions are attributed to the bound excitons in organic ligands and self-trapped excitons in [InCl5(H2O)]2- units, respectively. It is found that Sb doping in this 0D hybrid provides additional orange (590 nm) emission assigned to the 3P1 → 1S0 triplet radiative recombination. By adjusting the doping level, the emission color can be turned from turquoise to orange, and interestingly, a single-component white-light emission is realized by balancing the high-energy emission from organic ligand, the turquoise emission from [InCl5(H2O)]2-, and the orange one from [SbCl5(H2O)]2-. This work not only provides a new OIMH showing the single-component white light emission but also demonstrates the potential of In-based hybrids with hydrogen bonds for solid-state luminescence.

Dual-Template-Directed Zero-Dimensional Bismuth Chlorides: Structures, Luminescence, Photoinduced Chromism, and Enhanced Proton Conductivity

Zero-dimensional (0D) hybrid organic-inorganic bismuth halides have attracted immense scientific interest as promising candidates for lead-free materials. Here, by using a typical solvothermal method, two mixed-cation-phase 0D hybrid bismuth chlorides of [HPDA][H2PDA]BiCl6 (1) and [Hbzim][H2PA]BiCl6 (2) (PDA = bis(4-pyridyl)amine, bzim = benzimidazole, PA = 2-picolylamine) have been assembled based on a series of organic amine guests. Both compounds exhibit interesting photoluminescence phenomena, in which compound 1 exhibits a double emission property of blue fluorescence and yellow-green phosphorescence simultaneously, while compound 2 exhibits wide-band yellow-green emission under visible light excitation. The luminescence mechanism is explained by experiments and theoretical calculations. In view of the fact that halometallate units and the conjugated nitrogen heterocyclic systems can act as electron donors and electron acceptors, respectively, both compounds exhibit free radical-driven photochromism induced by electron transfer under xenon lamp irradiation at room temperature. In addition, benefiting from abundant hydrogen bond networks in structures, the two compounds show significant temperature-dependent proton conduction behavior in the range of 298-343 K, and the proton conductivity of both compounds is significantly improved after light irradiation. Our study demonstrates two novel hybrid mixed-cation-phase 0D hybrid bismuth halides with photoluminescence, photochromism, and photomodulated proton conduction properties, which enriches the dual-template-directed metal halide system and provides a feasible scheme for the synthesis of photoresponsive smart materials.

Sb3+ dopant triggered highly efficient emission in zero-dimensional organic-inorganic hybrid metal halides

Hybrid luminescent metal halides have attracted considerable attention for their structural diversity and versatility in photonic applications. Herein, we fabricate Sb3+ doped organic-inorganic hybrid metal halides (DMA)2CsInCl6 (DMA = [CH3NH2CH3]+) single crystal. Under ultraviolet light excitation, the crystals yield bright green emission at 550 nm with near-unity photoluminescence quantum efficiency (PLQY), which is attributed to the strong electronegativity and ns2 lone pairs of Sb3+ dopants. Given the slender rod-shaped semblance, bright green emission, near-unity PLQY, and large Stokes shift, Sb3+-doped (DMA)2CsInCl6 allows the potential optical waveguide applications.

Simplifying complexity: integrating color science for predictable full-color and on-demand persistent luminescence using industrial disperse dyes

Developing color-tunable ultralong room temperature phosphorescence (RTP) materials with variable afterglow is essential for applications in displays, sensors, information encryption, and optoelectronic devices. However, designing full-color ultralong RTP for persistent luminescence remains a significant challenge. Here, we propose a straightforward strategy to achieve predictable full-color afterglow using readily available disperse dyes in polymeric systems, via the phosphorescence resonance energy transfer (PRET) process. We incorporated the unconventional luminophore tetraacetylethylenediamine (TAED) into polyurethane (PU) to create a polymer host with green afterglow. By adding three typical disperse dyes as guests, we achieved a modulated afterglow covering the full visible light spectrum. Leveraging PRET processes between TAED and the disperse dyes, we achieved a prediction accuracy of 88.89% for afterglow color, surpassing well-developed coloration dye systems. This work thus introduces a novel method to obtain easily predictable ultralong RTP emission and establishes an on-demand design strategy for constructing disperse dye-based full-color afterglow, effectively linking fundamental color science to practical customization.

Highly efficient circularly polarized electroluminescence based on chiral manganese(ii) complexes

Currently reported circularly polarized luminescent devices are primarily based on rare earth and noble metal complexes or lead perovskite materials. Reports on electroluminescent devices employing eco-friendly luminescent materials are notably scarce. In this study, we strategically designed and synthesized manganese complexes featuring Binapo as the chiral ligand. The complex structure reveals a tetrahedral coordination configuration, with the R/S configurations exhibiting a mirror relationship. Leveraging the strong ligand field and chiral structural characteristics of Binapo, the enantiomers display red emission and exhibit significant circularly polarized luminescence with a circularly polarized luminescence asymmetric factor (g lum) of 5.1 × 10-3. The circularly polarized electroluminescent performance was investigated by using a solution processing method and host-guest doping strategy. Our efforts resulted in device performance with an external quantum efficiency (EQE) exceeding 4%, and its electroluminescent asymmetric factor (g EL) reached an impressive -8.5 × 10-3. This surpasses the performance of most devices relying on platinum (Pt) and iridium (Ir) metal complexes and perovskite related materials. Our work establishes a pathway for the development of cost-effective and environmentally friendly chiral electroluminescent materials and devices.

Optical activity levels of metal centers controlling multi-mode emissions in low-dimensional hybrid metal halides for anti-counterfeiting and information encryption

In-depth insight into the electronic competition principles between inorganic units and organic ligands proves to be extremely challenging for controlling multi-mode emissions in low-dimensional hybrid metal halides (LHMHs). Herein, an efficient blue emission from organic ligand was engineered in (DppyH)2MCl4 (Dppy = diphenyl-2-pyridylphosphine, M = Zn2+, Cd2+) due to the reverse type I band alignment constructed by optically inert units with nd10 shell electrons. By contrast, the optically active [MnCl4]2- with semi-fully filled 3d5 shell electrons prompts the band alignment of type II, resulting in the narrowband green emission of Mn2+, along with an energy transfer from DppyH+ to [MnCl4]2-. Beyond that, the band alignment of (DppyH)SbCl4 is further reversed to type I due to the strong stereochemical activity of 5s2 lone-pair electrons, resulting in the triplet-state (3P1 → 1S0) self-trapped exciton (STE) emission of [SbCl4]-. The conclusion is that the electronic configurations of metal centers govern the optical activity levels of inorganic units, which in turn controls the multi-mode emissions by maneuvering the band alignments. This research provides an enlightening perspective on the multi-mode emissions with tunable photoluminescence and resulting electronic transitions of LHMHs, whose derived emitters can be employed in anti-counterfeiting and information encryption.

Lead Bromide Complex in Tri-n-Octylphosphine Oxide Matrix with Bright Photoluminance and Exceptional Thermoplasticity

Metal halide materials have recently drawn increasing research interest for their excellent opto-electronic properties and structural diversity, but their resulting rigid structures render them brittle and poor formability during manufacturing. Here we demonstrate a thermoplastic luminant hybrid lead halide solid by integrating lead bromide complex into tri-n-octylphosphine oxide (TOPO) matrix. The construction of the hybrid materials can be achieved by a simple dissolution process, in which TOPO molecules act as the solvents and ligands to yield the monodispersed clusters. The combination of these functional units enables the near-room-temperature melt-processing of the materials into targeted geometry by simple molding or printing techniques, which offer possibilities for fluorescent writing inks with outstanding self-healing capacity to physical damage. The intermarriage between metal halide clusters with functional molecules expands the range of practical applications for hybrid metal halide materials.

Realizing Stable Luminescence in Antimony Doped Hybrid Tin(IV) Chloride toward Full Spectrum WLED and Anticounterfeiting Applications

The outstanding optical properties empower Sb3+-doped zero-dimensional hybrid metal halides as cutting-edge luminescent materials. In this research, we present an efficient hybrid tin chloride, TEA2SnCl6:Sb3+ (TEA = tetraethylammonium), with broad dual emission bands peaking in the blue and orange regions that arise from the singlet and triplet state emissions of [SbCl5]2-, respectively. TEA2SnCl6:Sb3+ demonstrates a high photoluminescence quantum yield (PLQY) of 83.5% under 328 nm excitation, while 358 nm light induces an orange emission with a PLQY of 92.5% and a low thermal quenching behavior (73.9% at 423 K). Benefiting from the appealing luminescence properties of TEA2SnCl6:Sb3+, a full spectrum white light-emitting diode (WLED) device and an anticounterfeiting model were constructed, affirming the potential use of Sb3+-doped TEA2SnCl6 hybrid metal halide in versatile application fields.

Boosting circularly polarized luminescence by optimizing off-centering octahedral distortion in zero-dimensional hybrid indium-antimony halides

Chiral zero-dimensional hybrid metal halides (0D HMHs) are being extensively studied as they can directly generate circularly polarized luminescence (CPL) with high photoluminescence quantum yields (PLQYs), yet improving their luminescence dissymmetry factor (g lum) remains a challenge. This study proposes a general strategy to boost the g lum value of chiral 0D HMHs by optimizing the off-centering distortion of inorganic octahedra. Accordingly, (R/S-MBA)2(2MA)In0.95Sb0.05Cl6 (MBA = α-methylbenzylammonium, 2MA = dimethylamine) and (R/S-MBA)2(3MA)In0.95Sb0.05Cl6 (3MA = trimethylamine) with near-unity PLQYs are accordingly synthesized. With increasing the from 0.012 to 0.020, the |g lum| is accordingly increased from 7.8 × 10-3 to 2.0 × 10-2. Notably, the |g lum| can be further boosted to an impressive value of 3.8 × 10-2 while maintaining near-unity PLQYs by continuously increasing the . Experimental results reveal that the choice of achiral ligands and varied Sb3+ dopant concentrations can modulate the distribution and strength of hydrogen bonds around indium-antimony halogen octahedra, respectively, thus regulating the parameter of octahedra in 0D hybrid metal halides. Additionally, light-emitting diodes with a polarization of 1.6% are fabricated. This work sheds light on the relationship between the distortion of inorganic octahedra and the g lum value.

Manipulating Chiroptical Activities in 0D Chiral Hybrid Manganese Bromides by Solvent Molecular Engineering

0D hybrid metal halides (0D HMHs) with fully isolated inorganic units provide an ideal platform for studying the correlations between chiroptical activities and crystal structures at atomic levels. Here, through the incorporation of different solvent molecules, a series of 0D chiral manganese bromides (RR/SS-C20H28N2)3MnBr8·2X (X = C2H5OH, CH3OH, or H2O) are synthesized to elucidate their chiroptical properties. They show negligible circular dichroism signals of Mn absorptions due to C2v-symmetric [MnBr4]2- tetrahedra. However, they display distinct circularly polarized luminescence (CPL) signals with continuously increased luminescence asymmetry factors (glum) from 10-4 (X = C2H5OH) to 10-3 (X = H2O). The increased glum value is structurally revealed to originate from the enhancement of [MnBr4]2- tetrahedral bond-angle distortions, due to the presence of different solvent molecules. Furthermore, (RR/SS-C20H28N2)MnBr4·H2O enantiomers with larger bond-angle distortions of [MnBr4]2- tetrahedra are synthesized based on hydrobromic acid-induced structural transformation of (RR/SS-C20H28N2)3MnBr8·2H2O enantiomers. Therefore, such (RR/SS-C20H28N2)MnBr4·H2O enantiomers exhibit enhanced CPL signals with |glum| up to 1.23 × 10-2. This work provides unique insight into enhancing chiroptical activities in 0D HMH systems.

Hybrid Eu(II)-bromide scintillators with efficient 5d-4f bandgap transition for X-ray imaging

Luminescent metal halides are attracting growing attention as scintillators for X-ray imaging in safety inspection, medical diagnosis, etc. Here we present brand-new hybrid Eu(II)-bromide scintillators, 1D type [Et4N]EuBr3·MeOH and 0D type [Me4N]6Eu5Br16·MeOH, with spin-allowed 5d-4f bandgap transition emission toward simplified carrier transport during scintillation process. The 1D/0D structures with edge/face -sharing [EuBr6]4- octahedra further contribute to lowing bandgaps and enhancing quantum confinement effect, enabling efficient scintillation performance (light yield ~73100 ± 800 Ph MeV-1, detect limit ~18.6 nGy s-1, X-ray afterglow ~ 1% @ 9.6 μs). We demonstrate the X-ray imaging with 27.3 lp mm-1 resolution by embedding Eu(II)-based scintillators into AAO film. Our results create the new family of low-dimensional rare-earth-based halides for scintillation and related optoelectronic applications.

Solvent-induced structural regulation and luminescence switching of hybrid copper(I) halides for encryption and anti-counterfeiting applications

Three luminescent copper(I) halides featuring distinct polyhedra were obtained via solvent volatilization, in which consecutive phase transformations of copper(I)-iodide units were triggered by methanol, along with visual luminescence switches, enabling applicability in information encryption and anti-counterfeiting. Such a multiple structural regulation in metal halides provides versatile design principles for photoluminescence tuning.

Multimode Luminescence Tailoring in PMA4Na(In,Sb)Cl8 Organic-inorganic Hybrid Metal Halide via Rigid Benzene Ring Induced Local Lattice Distortion

Low dimensional organic-inorganic hybrid metal halide materials have attracted extensive attention due to their superior optoelectronic properties. However, low photoluminescence quantum yields (PLQYs) caused by parity-forbidden transition hinder their further application in optoelectronic devices. Herein, a novel yellow-emitting PMA4Na(In,Sb)Cl8 (C7H10N+, PMA+) low-dimensional OIMHs single crystal with a PLQY as high as 88 % was successfully designed and synthesized, originating from the fact that the doping of Sb3+ effectively relaxes the parity-forbidden transition by strong spin-orbit (SO) coupling and Jahn-Teller (JT) interaction. The as-prepared crystal shows an efficient dual emission peaking 495 and 560 nm at low temperature, which are ascribed to different levels of 3P1→1S0 transitions of Sb3+ in [SbCl6]3- octahedral caused by JT deformation. Moreover, wide-range luminescence tailoring from cyan to orange can be achieved through adjusting excitation energy and temperature because of flexible [SbCl6]3- octahedral in the PNIC lattice. Based on a relative stiff lattice environment, the 560 nm yellow emission under 350 nm light excitation exhibits abnormal anti-thermal quenching from 8 to 400 K owing to the suppression of non-radiative transition. The multimode luminescence regulation enriches PMA4Na(In,Sb)Cl8 great potential in the field of optoelectronics such as temperature sensing, low temperature anti-counterfeiting and WLED applications.

Discerning the Structure-Photophysical Property Correlation in Zero-Dimensional Antimony(III)-Doped Indium(III) Halide Hybrids

Zero-dimensional (0D) metal halide hybrids incorporating optically emissive Sb3+ dopants have received huge research attention as a result of dopant-based visible emission for lighting and scintillation applications. Indeed, there have been a plethora of reports on Sb3+ doping of indium halide (In-X)-based 0D hybrids that show strong dopant emission with varied emission wavelengths (λem) and photoluminescence quantum yields (PLQYs). However, discerning the structure-luminescence relation in these 0D-doped hybrids remains challenging because it necessitates exquisite synthetic control on the local metal (dopant) halide geometry/site asymmetry. Demonstrated here is synthetic control that allows tuning of the local metal halide geometry of the Sb3+ dopants in 0D In-X hybrids utilizing five different organic cations. Experimental analysis of the series of Sb3+-doped In-X hybrids reveals a strong correlation between the extent of local metal halide geometry distortion and their photophysical properties (λem and PLQY). Density functional theory calculations of the doped compounds, characterizing ground- and excited-state structural distortions and energetics, reveal the origin of the extent of luminescence behavior. The experimental-computational results reported herein unravel the operative structure-luminescence relation in 0D Sb3+-doped In-X hybrids, provide insight into the emission mechanism, and open up avenues toward rational synthesis of strongly emissive materials with desired emission color for targeted applications.

Rigid Phase Formation and Sb3+ Doping of Tin (IV) Halide Hybrids toward Photoluminescence Enhancement and Tuning for Anti-Counterfeiting and Information Encryption

Multi-excitonic emitting materials in luminescent metal halides are emerging candidates for anti-counterfeiting and information encryption applications. Herein, ATPP2SnCl6 (ATPP=acetonyltriphenylphosphonium) phase was designed and synthesized by rationally choosing emissive organic reagent of ATPPCl and non-toxic stable metal ions of Sn4+, and Sb3+ was further doped into ATPP2SnCl6 to tune the photoluminescence with external self-trapped excitons emission. The derived non-toxic ATPP2SnCl6 shows multi-excitonic luminescent centers verified by optical study and differential charge-density from density functional theory calculations. Incorporation of Sb3+ dopants and the increasing concentrations induce the efficient energy transfer therein, thus enhancing photoluminescence quantum yield from 5.1 % to 73.8 %. The multi-excitonic emission inspires the creation of information encryption and decryption by leveraging the photoluminescence from ATPPCl to ATPP2SnCl6 host and ATPP2SnCl6 : Sb3+. This study facilitates the anti-counterfeiting application by employing solution-processable luminescent metal halides materials with excitation-dependent PL properties.

HCOO- Doping-Induced Multiexciton Emissions in Cs3Cu2I5 Crystals for Efficient X-Ray Scintillation

Self-trapped exciton (STE) luminescence, typically associated with structural deformation of excited states, has attracted significant attention in metal halide materials recently. However, the mechanism of multiexciton STE emissions in certain metal halide crystals remains largely unexplored. This study investigates dual luminescence emissions in HCOO- doped Cs3Cu2I5 single crystals using transient and steady-state spectroscopy. The dual emissions are attributed to intrinsic STE luminescence originating from the host lattice and extrinsic STE luminescence induced by external dopants, respectively, each of which can be triggered independently at distinct energy levels. Theoretical calculations reveal that multiexciton emission originates from structural distortion of the host and dopant STEs within the 0D lattice in their respective excited states. By meticulously tuning the excitation wavelength and selectively exciting different STEs, the dynamic alteration of color change in Cs3Cu2I5:HCOO- crystals is demonstrated. Ultimately, owing to an extraordinarily high photoluminescence quantum yield (99.01%) and a diminished degree of self-absorption in Cs3Cu2I5:HCOO- crystals, they exhibit remarkable X-ray scintillation characteristics with light yield being improved by 5.4 times as compared to that of pristine Cs3Cu2I5 crystals, opening up exciting avenues for achieving low-dose X-ray detection and imaging.

Low thermal quenching of metal halide-based metal-organic framework phosphor for light-emitting diodes

Phosphor-converted white light-emitting diodes (PC-WLEDs) have attracted considerable attention in solid-state lighting and display. However, urgent issues of thermal quenching and high cost remain formidable challenges. Herein, a novel metal-organic framework (MOF) phosphor [CdCl2(AD)] was facilely prepared using a mixture of CdCl2 and acridine (AD) under solvothermal conditions. It shows intensive green emission with a long lifetime of 31.88 ns and quantum yield of 65% while maintaining 95% and 84% of its initial emission intensity after remaining immersed in water for 60 days and being heated to 150 °C, respectively. The low thermal quenching of this MOF material is comparable to or can even exceed that of commercial inorganic phosphors. The combination of experiments and theoretical calculations reveals that the alternating arrangement of delocalized AD π-conjugated systems and CdCl2 inorganic chains through strong coordination bonds and π⋯π stacking interactions imparts the MOF phosphor with high thermal stability and optoelectronic performance. The successful fabrication of green and white LED devices by coating [CdCl2(AD)] and/or N630 red phosphor on a 365/460 nm commercial diode chip suggests a promising and potential alternative to commercial phosphors.

Synthesis and soft crystal structure-induced broad emission of (NH3C6H12NH3)InBr5·2H2O

We report a simple synthesis of a new lead-free zero-dimensional (0D) hybrid halide compound, (5P1)InBr5·2H2O [(5P1) = NH3C6H12NH3], which hosts isolated and distorted octahedra of [InBr5(H2O)]2-, surrounded by bulky asymmetric organic cations [(5P1)2+] and H2O molecules. The hybrid crystals exhibit broad self trapped excitonic (STE) emission due to strong anharmonic soft structure.

Dimethylamine Copper(I) Halide Single Crystals: Structure, Physical Properties, and Scintillation Performance

Hybrid copper(I) halides have garnered a significant amount of attention as potential substitutes in luminescence and scintillation applications. Herein, we report the discovery and crystal growth of new zero-dimensional compounds, (C2H8N)3Cu2I5 and (C2H8N)4Cu2Br6. The bromide and iodide have a triclinic structure with space group P1̅ and an orthorhombic structure with space group Pnma, respectively. (C2H8N)3Cu2I5 exhibits cyan emission peaking at 504 nm with a photoluminescence quantum yield (PLQY) of 34.79%, while (C2H8N)4Cu2Br6 shows yellowish-green emission peaking at 537 nm with a PLQY of 38.45%. The temperature-dependent photoluminescence data of both compounds were fitted to theoretical models, revealing that nonradiative intermediate states significantly affect thermal quenching and antiquenching. Electron-phonon interactions, the origin of emission line width broadening and peak shifting, were also investigated via fittings. The scintillation properties of (C2H8N)3Cu2I5 were evaluated, and an X-ray imaging device was successfully fabricated using (C2H8N)3Cu2I5. This work demonstrates the potentiality of copper halides in lighting and X-ray imaging applications.

A Luminescent Hybrid Bimetallic Halide Family with Solvent-Coordinated Rare Earth and Alkaline Earth Metals

Hybrid metal halides are an extraordinary class of optoelectronic materials with extensive applications. To further diversify and study the in-depth structure-property relations, we report here a new family of 21 zero-dimensional hybrid bimetallic chlorides with the general formula A(L)n[BClm] (A=rare earth (RE), alkaline earth metals and Mn; L=solvent ligand; and B=Sb, Bi and Te). The RE(DMSO)8[BCl6] (RE=La, Ce, Sm, Eu, Tb, and Dy; DMSO=dimethyl sulfoxide) series shows broadband emission attributed to triplet radiative recombination from Sb and Bi, incorporating the characteristic emission of RE metals, where Eu(DMSO)8[BiCl6] shows a staggering PL quantum yield of 94 %. The pseudo-octahedral [SbCl5] with Cl vacancy in AII(DMSO)6[SbCl5] (AII=Mg, Ca and Mn) and the square pyramidal [SbCl5] in AII(TMSO)6[SbCl5] (TMSO=tetramethylene sulfoxide) enhance the stereoactive expression of the 5 s2 lone pairs of Sb3+, giving rise to the observation of dual-band emission of singlet and triplet emission, respectively. A series of Te(IV) analogues have been characterized, showing blue-light-excitable single-band emission. This work expands the materials space for hybrid bimetallic halides with an emphasis on harnessing the RE elements, and provides important insights into designing new emitters and regulating their properties.

Recent Advances in Fast-Decaying Metal Halide Perovskites Scintillators

Fast-decaying scintillators show subnanoseconds or nanoseconds lifetime and high time resolution, making them important in nuclear physics, medical diagnostics, scientific research, and other fields. Metal halide perovskites (MHPs) show great potential for scintillator applications owing to their easy synthesis procedure and attractive optical properties. However, MHPs scintillators still need further improvement in decay lifetime. To optimize the decay lifetime, great progress has been achieved recently. In this Perspective, we first summarize the structural characteristics of MHPs in various dimensions, which brings different exciton behaviors. Then, recent advances in designing fast-decaying MHPs according to different exciton behaviors have been concluded, focusing on the photophysical mechanisms to achieve fast-decaying lifetimes. These advancements in decay lifetimes could facilitate the MHPs scintillators in advanced applications, such as time-of-flight positron emission tomography (TOF-PET), photon-counting computed tomography (PCCT), etc. Finally, the challenges and future opportunities are discussed to provide a roadmap for designing novel fast-decaying MHPs scintillators.

High-efficiency color-tunable ultralong room-temperature phosphorescence from organic-inorganic metal halides via synergistic inter/intramolecular interactions

Materials exhibiting highly efficient, ultralong and multicolor-tunable room-temperature phosphorescence (RTP) are of practical importance for emerging applications. However, these are still very scarce and remain a formidable challenge. Herein, using precise structure design, several novel organic-inorganic metal-halide hybrids with efficient and ultralong RTP have been developed based on an identical organic cation (A). The original organic salt (ACl) exhibits red RTP properties with low phosphorescence efficiency. However, after embedding metals into the organic salt, the changed crystal structure endows the resultant metal-halide hybrids with excellent RTP properties. In particular, A2ZnCl4·H2O exhibits the highest RTP efficiency of up to 56.56% with a long lifetime of up to 159 ms. It is found that multiple inter/intramolecular interactions and the strong heavy-atom effect of the rigid metal-halide hybrids can suppress molecular motion and promote the ISC process, resulting in highly stable and localized triplet excitons followed by highly efficient RTP. More crucially, multicolor-tunable fluorescence and RTP achieved by tuning the metal and halogen endow these materials with wide application prospects in the fields of multilevel information encryption and dynamic optical data storage. The findings promote the development of phosphorescent metal-halide hybrids for potential high-tech applications.

Efficient Large-Area (81 cm2) Ternary Copper Halides Light-Emitting Diodes with External Quantum Efficiency Exceeding 13% via Host-Guest Strategy

Ternary copper (Cu) halides are promising candidates for replacing toxic lead halides in the field of perovskite light-emitting diodes (LEDs) toward practical applications. However, the electroluminescent performance of Cu halide-based LEDs remains a great challenge due to the presence of serious nonradiative recombination and inefficient charge transport in Cu halide emitters. Here, the rational design of host-guest [dppb]2Cu2I2 (dppb denotes 1,2-bis[diphenylphosphino]benzene) emitters and its utility in fabricating efficient Cu halide-based green LEDs that show a high external quantum efficiency (EQE) of 13.39% are reported. The host-guest [dppb]2Cu2I2 emitters with mCP (1,3-bis(N-carbazolyl)benzene) host demonstrate a significant improvement of carrier radiative recombination efficiency, with the photoluminescence quantum yield increased by nearly ten times, which is rooted in the efficient energy transfer and type-I energy level alignment between [dppb]2Cu2I2 and mCP. Moreover, the charge-transporting mCP host can raise the carrier mobility of [dppb]2Cu2I2 films, thereby enhancing the charge transport and recombination. More importantly, this strategy enables a large-area prototype LED with a record-breaking area up to 81 cm2, along with a decent EQE of 10.02% and uniform luminance. It is believed these results represent an encouraging stepping stone to bring Cu halide-based LEDs from the laboratory toward commercial lighting and display panels.

Efficient Ultraviolet Circularly Polarized Luminescence in Zero-Dimensional Hybrid Cerium Bromides

Ultraviolet circularly polarized luminescence (UV-CPL) with high photon energy shows great potential in polarized light sources and stereoselective photopolymerization. However, developing luminescent materials with high UV-CPL performance remains challenging. Here, we report a pair of rare earth Ce3+-based zero-dimensional (0D) chiral hybrid metal halides (HMHs), R/S-(C14H24N2)2CeBr7, which exhibits characteristic UV emissions derived from the Ce 5d-4f transition. The compounds show simultaneously high photoluminescent quantum yields of (32-39)% and large luminescent dissymmetry factor (|glum|) values of (1.3-1.5)×10-2. Thus, the figures of merits of R/S-(C14H24N2)2CeBr7 are calculated to be (4.5-5.8)×10-3, which are superior to the reported UV-CPL emissive materials. Additionally, nearly 91 % of their PL intensities at 300 K can be well preserved at 380 K (LED operating temperature) without phase transition or decomposition, demonstrating the excellent structural and optical thermal stabilities of R/S-(C14H24N2)2CeBr7. Based on these enantiomers, the fabricated UV-emitting CP-LEDs exhibit high polarization degrees of ±1.0 %. Notably, the UV-CPL generated from the devices can significantly trigger the enantioselective photopolymerization of diacetylene with remarkable stereoselectivity, and consequently yield polymerized products with the anisotropy factors of circular dichroism (gCD) up to ±3.9×10-2, outperforming other UV-CPL materials and demonstrating their great potential as UV-polarized light sources.

Multifunctional Phosphor with High-Efficient Near-Infrared Emission Based on Antimony-Zinc Halides

Metal halide-based broadband near-infrared (NIR) luminescent materials face problems such as complicated preparation, high cost, low photoluminescence quantum yield, and high excitation energy. Here, incorporating Sb3+ and Br- into (C20H20P)2ZnCl4 crystals allowed for the achievement of efficient broadband near-infrared emission under 400 nm excitation while maintaining satisfactory environmental and thermal stability. The compounds exhibit a broad range of emission bands from 550 to 1050 nm, with a photoluminescence quantum yield of 93.57%. This is a groundbreaking achievement for organic-inorganic hybrid metal halide NIR luminescent materials. The near-infrared emission is suggested to originate from [SbX5]2-, as supported by the femtosecond transient absorption spectra and density-functional theory calculations. This phosphor-based NIR LEDs successfully demonstrate potential applications in night vision, medical imaging, information encryption, and anticounterfeiting.