Hybrid Metal Halide Research Articles

White light emission in 0D halide perovskite [(CH3)3S]2SnCl6·H2O crystals through variation of doping ns2 ions

With the rapid development of white LEDs, the research of new and efficient white light emitting materials has attracted increasing attention. Zero dimensional (0D) organic–inorganic hybrid metal halide perovskites with superior luminescent property are promising candidates for LED application, due to their abundant and tailorable structure. Herein, [(CH3)3S]2SnCl6·H2O is synthesized as a host for dopant ions Bi3+ and Sb3+. The Sb3+ doped, or Bi3+/Sb3+ co-doped, [(CH3)3S]2SnCl6·H2O has a tunable optical emission spectrum by means of varying dopant ratio and excitation wavelength. As a result, we can achieve single-phase materials suitable for emission ranging from cold white light to warm white light. The intrinsic mechanism is examined in this work, to clarify the dopant effect on the optical properties. The high stability of title crystalline material, against water, oxygen and heat, makes it promising for further application.Graphical

Manganese (II) Halides for X‐Ray Imaging and Moisture Detection

AbstractOrganic–inorganic hybrid metal halides are widely used in X‐ray detection and imaging due to their high X‐ray absorption efficiency, ease of synthesis, and efficient luminescence. However, the issue of lead toxicity remains a concern. In this study, non‐toxic, 0D 2,2′‐(Ethylenedioxy)bis(ethylamine) manganese (II) bromide (EDBEMnBr4) is synthesized using the simple mechanical grinding method and the solution method that exhibits intense green emission at ≈525 nm. Moreover, the change of structure under the influence of temperature and water significantly affects its fluorescence color under UV light. Scintillator materials with and without moisture exposure showed spatial resolutions of 7 and 4 lp mm−1, and low detection limits of 4.62 and 5.25 µGyair s−1, respectively, meeting medical industry standards (<5.5 µGyair s−1). Furthermore, based on the apparent change in luminescence color triggered by moisture for EDBEMnBr4, a preliminary attempt is made to apply it to humidity monitoring showing that the boundary of color change has a good linear dependence on humidity and time. This work provides new opportunities for Mn‐based metal halides in both X‐ray detection as well as moisture detection.

1D Tin(II)‐Based Chiral Hybrid Perovskite Single Crystals with Extremely Distorted Inorganic Chains for Second Harmonic Generation

AbstractThe organic–inorganic hybrid metal halides with chiral structures have attracted great attentions in the field of optoelectronic functional materials, especially for nonlinear optics. To date, second harmonic generation (SHG) properties of several classes of chiral hybrid halides with different metal ions have been reported. However, SHG‐active tin(II)‐based chiral materials are rarely explored, hindering deep understandings of the relationship between their structures and SHG properties. Herein, Sn2+ ions are successfully introduced into chiral hybrid perovskites, and four new species of chiral hybrid perovskites (R/S‐α‐PEA)SnX3 (X = Cl and Br, PEA = phenylethylammonium) are obtained. The as‐grown crystals are in P212121 space group, with highly distorted [SnX6] octahedral units forming 1D chain structures in the lattice, due to the effect of stereochemically active lone pair 5s2 electrons in Sn2+. Such crystals have an SHG response of ≈1.4× Y‐cut α‐quartz for (S‐α‐PEA)SnBr3 and ≈0.9× Y‐cut α‐quartz for (S‐α‐PEA)SnCl3 at 1020 nm excitation, with high polarization ratio of SHG signals as well as wide bandgaps and transparency windows in the meanwhile. This work opens up a new platform for discovering more novel tin(II)‐based chiral perovskites with superior nonlinear optical properties in the future.

The correlation between structural factors and Stokes shifts in zero-dimensional Antimony(III) halides

Zero-dimensional (0D) hybrid metal halides (HMHs) have recently garnered significant attention as promising light emitters due to their distinctively Stokes-shifted broadband emissions resulting from self-trapped excitons (STEs). However, the influence of crystalline structures on the Stokes shift remains inadequately understood. Herein, we design and synthesize a series of 0D (Ph4P)2SbCl5-xBrx (Ph4P = tetraphenylphosphonium, x = 0–5) compounds to elucidate the intrinsic relationship between structural factors and the Stokes shift in 0D Sb(III) halides. Our comprehensive investigations into their crystalline structures and photoluminescence (PL) properties unveil that the Stokes shift correlates with intra- and inter-pyramidal [SbCl5-xBrx]2- units. Specifically, a shorter vertical Sb–Cl bond within the square pyramid, coupled with a greater Sb⋯Sb distance between the pyramidal units, facilitates significant structural relaxation in excited states, resulting in a larger Stokes shift, and vice versa. Notably, this principle applies not only within identical space groups but also across different crystal systems. Furthermore, our findings are supported by analyses of the structures and PL properties of other reported 0D Sb(III) halides with square pyramidal coordination. This study elucidates the structure-dependent nature of the Stokes shift in 0D Sb(III) halides, offering a novel avenue for the design of functional 0D metal halide materials.

Mn-Doped M2CdCl4 (M = CH3NH3+, C2H8N+, and C3H10N+) Layered Hybrid Perovskite and Its Flexible Film Based on Simple Mechanochemical Synthesis.

Layered hybrid perovskites show significant advantages in the field of optoelectronics. However, the low quantum efficiency and complex preparation methods limit their applications. In this work, we developed a series of perovskite powders with a two-dimensional (2D) layered structure of organic-inorganic hybrid metal halides M2CdCl4:x%Mn (M = CH3NH3+, C2H8N+, C3H10N+) via facile mechanochemical methods. The prepared manganese Mn-doped MA2CdCl4 produces orange emission at 605 nm under both 254 and 420 nm excitation, which originates from a dual excitation channel competition mechanism, and its excitation channel could be changed with the increase of Mn2+ ion concentration. Typically, MA2CdCl4:20%Mn powder exhibits high photoluminescence quantum yield (PLQY) close to 90% at 605 nm due to the organic amine ions enlarging the Mn-Mn interlayer distances. In addition, we prepared MA2CdCl4:x%Mn@PVA flexible films, which also exhibit good luminescence at 254 nm excitation and were unexpectedly found to have a better response to Cs+, which could be a candidate for anticounterfeiting applications.

Bright Circularly Polarized Mechanoluminescence from 0D Hybrid Manganese Halides.

Hybrid metal halides (HMHs) with efficient circularly polarized luminescence (CPL) have application prospects in many fields, due to their abundant host-guest structures and high photoluminescence quantum yield (PLQY). However, CPLs in HMHs are predominantly excited by light or electricity, limiting their use in multivariate environments. It is necessary to explore a novel excitation method to extend the application of chiral HMHs as smart stimuli-responsive optical materials. In this work, an enantiomeric pair of 0D hybrid manganese bromides, [H2(2R,4R)-(+)/(2S,4S)-(-)-2,4-bis(diphenylphosphino)pentane]MnBr4 [(R/S)-1] is presented, which exhibits efficient CPL emissions with near-unity PLQYs and high dissymmetry factors of ± 2.0 × 10-3. Notably, (R/S)-1 compounds exhibit unprecedented and bright circularly polarized mechanoluminescence (CPML) emissions under mechanical stimulation. Moreover, (R/S)-1 possess high mechanical force sensitivities with mechanoluminescence (ML) emissions detectable under 0.1 N force stimulation. Furthermore, this ML emission exhibits an extraordinary antithermal quenching effect in the temperature range of 300-380 K, which is revealed to originate from a thermal activation energy compensation mechanism from trap levels to Mn(II) 4T1 level. Based on their intriguing optical properties, these compounds as chiral force-responsive materials are demonstrated in multilevel confidential information encryption.

Near-Unity Green Luminescent Hybrid Manganese Halides as X-ray Scintillators.

The increasing demands in optoelectronic applications have driven the advancement of organic-inorganic hybrid metal halides (OIMHs), owing to their exceptional optical and scintillation properties. Among them, zero-dimensional (0D) low-toxic manganese-based scintillators have garnered significant interest due to their exceptional optical transparency and elevated photoluminescence quantum yields (PLQYs), making them promising for colorful light-emitting diodes and X-ray imaging applications. In this study, two OIMH single crystals of (Br-PrTPP)2MnBr4 (Br-PrTPP = (3-bromopropyl) triphenylphosphonium) and (Br-BuTPP)2MnBr4 (Br-BuTPP = (4-bromobutyl) triphenylphosphonium) were prepared via a facile saturated crystallization method. Benefiting from the tetrahedrally coordinated [MnBr4]2- polyhedron, both of them exhibited strong green emissions peaked at 517 nm owing to the d-d electron transition of Mn2+ with near-unity PLQYs of 99.33 and 86.85%, respectively. Moreover, benefiting from the high optical transparencies and remarkable luminescence properties, these manganese halides also exhibit excellent radioluminescent performance with the highest light yield of up to 68,000 photons MeV-1, negligible afterglow (0.4 ms), and linear response to X-ray dose rate with the lowest detection limit of 45 nGyair s-1. In X-ray imaging, the flexible film made by the composite of (Br-PrTPP)2MnBr4 and PDMS shows an ultrahigh spatial resolution of 12.78 lp mm-1, which provides a potential visualization tool for X-ray radiography.

From C4H7N2Ge0.4Sn0.6Br3 to C6H11N2Ge0.4Sn0.6Br3: Effective Modulation of the Second Harmonic Generation Effect and Optical Band Gap by Planar π-Conjugated Organic Cation Size.

In the search for nonlinear optical (NLO) materials with excellent overall performance, we have devoted ourselves to organic-inorganic hybrids consisting of anionic groups containing stereochemically active lone-pair (SCALP) electron cations and organic planar π-conjugated group cations. Accordingly, in this paper, two novel organic-inorganic hybrid metal halides, C4H7N2Ge0.4Sn0.6Br3 (I) and C6H11N2Ge0.4Sn0.6Br3 (II), have been synthesized. The powder second-harmonic technique shows that both C4H7N2Ge0.4Sn0.6Br3 and C6H11N2Ge0.4Sn0.6Br3 have moderately strong second-order nonlinear optical effects, which are about 2.03 (I) and 1.16 (II) times that of KH2PO4 (KDP), respectively. They also have different optical band gaps of 2.75 (I) and 2.88 eV (II) due to the different sizes of the organic cations, and their photoluminescent and thermal properties were also investigated. This work provides new structural insights for the design and modulation of organic-inorganic hybrid halide materials with multiple excellent optical properties.

Recent Advances in Room-Temperature Phosphorescence Metal-Organic Hybrids: Structures, Properties, and Applications.

Metal-organic hybrid (MOH) materials with room-temperature phosphorescence (RTP) have drawn attention in recent years due to their superior RTP properties of high phosphorescence efficiency and ultralong emission lifetime. Great achievement has been realized in developing MOH materials with high-performance RTP, but a systematic study on MOH materials with RTP feature is lacking. This review highlights recent advances in metal-organic hybrid RTP materials. The molecular packing, the photophysical properties, and their applications of metal-organic hybrid RTP materials are discussed in detail. Metal-organic hybrid RTP materials can be divided into six parts: coordination polymers, metal-organic frameworks (MOFs), metal-halide hybrids, organic ionic crystals, organic ionic polymers, and organic-inorganic hybrid perovskites. These RTP materials have been successfully applied in time-resolved data encryption, fingerprint recognition, information logic gates, X-ray imaging, and photomemory. This review not only provides the basic principles of designing RTP metal-organic hybrids, but also propounds the future research prospects of RTP metal-organic hybrids. This review offers many effective strategies for developing metal-organic hybrids with excellent RTP properties, thus satisfying practical applications.

Efficient Deep‐Blue Light‐Emitting 2D (100)‐Oriented Perovskites and Spectral Broadening by Exciton Self‐Trapping for White‐light Emissions

AbstractEfficient narrow deep‐blue and broadband emissions in layered 2D organic–inorganic hybrid metal halide perovskites (MHPs) are attracting more attention and need further study. In this work, two (100)‐oriented 2D organic‐inorganic hybrid MHPs of (TFI)2PbBr4 and (TFI)2PbCl4·H2O (TFI = 4‐(trifluoromethyl)‐1H‐imidazole) with efficient deep‐blue and bluish‐white emissions are synthesized and the photoluminescence quantum yields (PLQYs) reached up to 81.21% and 20.23%, respectively. As both intrinsic lattice distortions of two crystals with similar crystal structure are almost negligible, they have theoretical deep‐blue emissions empirically. However, the halogen substitution of chlorine (Cl) by bromine (Br) broadened the deep‐blue photoluminescence to a bluish‐white area. Here, the spectral broadening phenomenon is discussed in detail. The (TFI)2PbBr4 film shows a narrow emission with a 16 nm full width at half maximum (FWHM) peaking at 435 nm upon excitation, and an ultraviolet‐pumped light‐emitting diode (LED) prepared by bluish‐white (TFI)2PbCl4·H2O phosphor shows a color rendering index (CRI) of ≈93 and a related color temperature (CCT) of 4162K, indicating their potential applications in deep‐blue and white LEDs, respectively.

Antimony Doped Hybrid Zinc Halide Crystals with Tunable Light Emission and Long‐Term Stability

AbstractAs a class of emerging photoluminescent materials, hybrid halide crystals have drawn research attention for their potential application in the fields of light‐emitting, security, and waveguide. Nevertheless, hybrid halide crystals containing antimony with long‐term stability and tunable light emission are still increasingly in demand. In this work, serial new hybrid halide crystals (BZA)2ZnCl4·2H2O:xSb3+ (x = 0–0.2, x represents the reaction ratio) and (BZA)2SbCl5 are synthesized (BZA = 2,4‐diamino‐6‐phenyl‐1,3,5‐triazine). In (BZA)2ZnCl4·2H2O:xSb3+ crystals, Sb3+ cations replace partial Zn2+ cations to form [SbCl4]− tetrahedron. Red light emission caused by the substitution of Sb3+ for Zn2+ enhances as the doping rate increases, resulting in the tunable emission from light blue to pink and finally to dark red. There are two kinds of Sb3+ in (BZA)2SbCl5 crystal. Sb(1) has a sixfold coordination with Cl to form a [Sb(1)Cl5]∞ 1D zigzag chain. Sb(2) atom adopts a fivefold coordination with Cl and is separated from each other by BZA+ cations. (BZA)2SbCl5 crystal shows bright orange‐yellow light emission with a photoluminescence quantum yield of 45%. Moreover, the organic–inorganic hybrid metal halide crystals containing antimony have excellent long‐term stability, with phase and luminescence keeping nearly unchanged after more than six months in ambient air.

Sb3+-Doped Indium-Based Metal Halide (Gua)3InCl6 with Efficient Yellow Emission.

In recent years, low-dimensional organic-inorganic hybrid metal halides (OIHMHs) have shown excellent photophysical properties due to their quantum structure, adjustable energy levels, and energy transfer between inorganic and organic components, which have attracted extensive attention from researchers. Herein, we synthesize a zero-dimensional (0D) OIHMH, Sb3+:(Gua)3InCl6, by introducing Sb3+ into (Gua)3InCl6, which undergoes a significant enhancement of the emission peak at 580 nm with the photoluminescence quantum yield (PLQY) boosted from 17.86 to 95.72% when excited at 340 nm. This boost in photoluminescence of the doped sample was studied by combining ultrafast femtosecond transient absorption, temperature-dependent photoluminescence (PL) spectra, and density functional theory (DFT) calculation, revealing the process of self-trapped exciton (STE) recombination to emit light at both Sb and In sites in this 0D structure simultaneously. This material with the lowest dark STE level at the In site for emission in the undoped sample can amazingly yield very strong emission in the doped sample, which has never been observed before. Finally, we tested its application in a photoelectric device. This work not only helps to gain a deeper understanding of the formation of STEs in In-based halides but also plays a certain guiding role in the design of new luminescent materials.

Stimuli‐Responsive Emission from Hybrid Metal Halides

AbstractStimuli‐responsive photoluminescent (PL) materials have attracted considerable attention in recent years owing to their potential applications in anti‐counterfeiting, information encryption, and sensing. Further investigations of the transformation mechanism and potential applications of stimulus‐responsive PL materials are considerably important. In the current study, an organic–inorganic metal halide, C9H15N3SbCl5 ([C9H13N3]2+ is a 1‐(2‐pyridyl) piperazine cation) is obtained, which exhibits a 0D structure with P‐1 space group. At room temperature, when excited by UV light, the C9H15N3SbCl5 single crystals exhibit unimodal blue light emission at 405 nm, and grinding or hydrostatic pressure induces double‐peak emissions at 405 and 650 nm. Interestingly, double‐emission samples can be restored to single‐emission samples by short annealing or storage in air for 2 weeks, and this process is reversible. Luminescence response to mechanical stimuli can also be achieved in the presence of hydrochloric acid and water. Spectral analysis and the analysis of the microstructural changes revealed that the structural modifications of the inorganic group play a pivotal role in the response to the stimulus. Finally, a composite film device based on C9H15N3SbCl5 is prepared to demonstrate the potential of these smart materials in anti‐counterfeiting and sensing applications.

Recent developments in perovskite materials, fabrication techniques, band gap engineering, and the stability of perovskite solar cells

Organic-inorganic hybrid metal halide perovskite solar cells (PSC) represent a novel class of optoelectronic semiconductors that have garnered significant attention from photovoltaic researchers globally. This is due to their continually improving efficiency, straightforward solution processing methods, use of lightweight and cost-effective materials, and other notable features. The advantageous properties of perovskite materials, such as superior charge transport, tunable band gap, and distinctive electronic structure, contribute to their appeal. Over the past 6 to 7 years, diverse device architectures and fabrication techniques for PSC have emerged, achieving an impressive power conversion efficiency (PCE) of 25.7%. This review article primarily focuses on recent advancements in PSC fabrication techniques, synthesis, device architecture, charge transport mechanisms, band gap engineering, and stability. Additionally, it provides a summary of recently reported materials used in various layers of PSC, including the perovskite layer, as well as electron and hole transport layers. Lastly, the article outlines the challenges faced in the development of PSC, offers recommendations, and suggests potential directions for future research to guide the field forward.

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.

(C13N3H14)2MBr4 (M = Zn, Cd): two novel hybrid metal halides with balanced integrated nonlinear optical performance

Two new hybrid metal halides (C13N3H14)2MBr4 (M = Zn, Cd) were obtained by three-in-one-strategy, exhibiting comprehensive high-performance NLO properties. Besides, the composition-structure-NLO properties relationship is well studied.

Direct X-ray detectors made of zero-dimensional hybrid metal halide perovskite single crystals

A novel zero-dimensional cadmium hybrid metal halide (C19H18P)2CdCl4 single crystal was synthesized by inserting (C19H18P)+ into a [CdCl4]2− tetrahedron lattice through a slow volatilization method, which was proved to be a promising X-ray detector.

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.

Designing guanidine-based lead-free hybrid indium perovskites with highly efficient intrinsic broadband emissions

Recent advances in luminescent materials have highlighted zero-dimensional (0D) hybrid metal halides as highly efficient candidates.

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.