Hybrid Organic-inorganic Metal Halide Research Articles

Chiral induction and Sb3+ doping in indium halides to trigger second harmonic generation and circularly polarized luminescence

Recently, organic-inorganic hybrid metal halides (HMHs) have attracted extensive attention as promising multifunctional materials by virtue of their structural diversity and tunable photophysical properties. However, it remains a challenge to design HMHs with specific functions on demand. Herein, by introducing R/S-methylbenzylamine (R/S-MBA) and doping Sb3+, we have achieved both second harmonic generation (SHG) and circularly polarized luminescence (CPL) properties in lead-free indium halides. The introduction of chiral organic cations can break the symmetry and induce the indium halides to crystallize in the chiral space group. The Sb3+ with ns2 electronic configuration can serve as the dopants to promote the formation of self-trapped excitons, so as to activate highly efficient luminescence. As a result, the as-prepared Sb3+ doped (R/S-MBA)3InCl6 show not only SHG responses but also CPL signals with luminescence dissymmetry factor of −5.3 × 10−3 and 4.7 × 10−3. This work provides a new inspiration for the exploitation of chiral multifunctional materials.

Dimension-Controlled Synthesis of Hybrid-Mixed Halide Perovskites for Solar Cell Application.

Despite the rapid improvement of photovoltaic (PV) efficiency in hybrid organic-inorganic metal halide perovskites (HOIPs), the fabrication procedure of a compact thin film in a large-area application is still a tedious work. Apart from the quality of the thin film, the stability of the perovskite materials and the expensive organic hole transport layer (HTL) within the HOIP-based PV device are the major issues that need to be addressed prior to their commercialization. Herein, a unique glass rod-based facile fabrication technique for producing a compact and stable thin film utilizing a mixed-halide-based perovskite precursor solution is demonstrated. The fabricated devices deliver high photoconversion efficiency (PCE) without the use of any HTL and show an excellent stability under ambient conditions. By varying the organic CH3NH3I (MAI) and inorganic PbBr2 content, perovskite materials with different dimensions, i.e., 3D, 2D, and 1D, are synthesized to produce an active layer for PV devices. Although a 2D single-halide perovskite is reported earlier, herein two different mixed-halide 2D perovskites, i.e., MA2PbI2Br2 and MAPb2IBr4, are synthesized successfully, and their performance is compared in detail along with that of 1D and 3D mixed-halide perovskites. The facile synthesized mixed-halide 2D-based MA2PbI2Br2 perovskite shows a PCE of 10.14% with a high stability of 92% after 100 days without encapsulation, which is much superior as compared to that of the mixed-halide 3D MAPbIBr2. The semiconducting behavior as well as the nature of the bandgap of the synthesized compounds is examined by pursuing density functional theory calculations. Specifically, the role of iodine doping to modify the electronic band structure is investigated, and introduction of iodine is found to reduce the effective masses of both electrons and holes in the perovskite material.

Chiral Hybrid Germanium(II) Halide with Strong Nonlinear Chiroptical Properties

AbstractDue to the pronounced anisotropic response to circularly polarized light, chiral hybrid organic–inorganic metal halides have been regarded as promising candidates for the application in nonlinear chiroptics, especially for the second‐harmonic generation circular dichroism (SHG‐CD) effect. However, designing novel lead‐free chiral hybrid metal halides with large anisotropy factors and high laser‐induced damage thresholds (LDT) of SHG‐CD remains challenging. Herein, we develop the first chiral hybrid germanium halide, (R/S‐NEA)3Ge2I7⋅H2O (R/S‐NGI), and systematically investigated its linear and nonlinear chiroptical properties. S‐NGI and R‐NGI exhibit large anisotropy factors (gSHG‐CD) of 0.45 and 0.48, respectively, along with a high LDT of 38.46 GW/cm2; these anisotropy factors were the highest values among the reported lead‐free chiral hybrid metal halides. Moreover, the effective second‐order nonlinear optical coefficient of S‐NGI could reach up to 0.86 pm/V, which was 2.9 times higher than that of commercial Y‐cut quartz. Our findings facilitate a new avenue toward lead‐free chiral hybrid metal halides, and their implementation in nonlinear chiroptical applications.

Chiral Hybrid Germanium(II) Halide with Strong Nonlinear Chiroptical Properties.

Due to the pronounced anisotropic response to circularly polarized light, chiral hybrid organic-inorganic metal halides have been regarded as promising candidates for the application in nonlinear chiroptics, especially for the second-harmonic generation circular dichroism (SHG-CD) effect. However, designing novel lead-free chiral hybrid metal halides with large anisotropy factors and high laser-induced damage thresholds (LDT) of SHG-CD remains challenging. Herein, we develop the first chiral hybrid germanium halide, (R/S-NEA)3 Ge2 I7 ⋅H2 O (R/S-NGI), and systematically investigated its linear and nonlinear chiroptical properties. S-NGI and R-NGI exhibit large anisotropy factors (gSHG-CD ) of 0.45 and 0.48, respectively, along with a high LDT of 38.46 GW/cm2 ; these anisotropy factors were the highest values among the reported lead-free chiral hybrid metal halides. Moreover, the effective second-order nonlinear optical coefficient of S-NGI could reach up to 0.86 pm/V, which was 2.9 times higher than that of commercial Y-cut quartz. Our findings facilitate a new avenue toward lead-free chiral hybrid metal halides, and their implementation in nonlinear chiroptical applications.

Large Phase-Transition Temperature Enhancement Achieved in a Layered Lead Iodide Hybrid Crystal by H/F Substitution.

Organic-inorganic hybrid metal halides with structural flexibility and solution processability have been widely investigated for different application scenarios. However, the effective construction of phase-transition materials with a high phase-transition temperature (Ttr) for potential practical applications remains a great challenge, and reports on the regulation of Ttr with significant enhancement have been rare. In this manuscript, we have realized a large Ttr increase of 148 K in a layered hybrid lead iodide crystal (4-FTMBA)4Pb3I10 (4-FTMBA = 4-fluoro-N,N,N-trimethylbenzenaminium) by the H/F substitution strategy. Compared to the parent (TMBA)4Pb3I10 (TMBA = N,N,N-trimethylbenzenaminium), H/F substitution preserves the structural framework and crystal symmetry in (4-FTMBA)4Pb3I10. The introduction of heavier fluorine will significantly increase the motion barrier for the order-disorder transition, resulting in the remarkably improved Ttr. Temperature-dependent crystal structures, Raman spectra, and dielectric analyses well support the phase-transition behavior. In addition, evident thermochromism with a tunable direct band gap in (4-FTMBA)4Pb3I10 has been observed using UV-vis spectra. To the best of our knowledge, the achieved Ttr enhancement of 148 K by H/F substitution is the highest among the organic-inorganic hybrid lead halide phase-transition materials. This finding would greatly inspire the rational design of functional materials with high performance.

A High-Rigidity Organic-Inorganic Metal Halide Hybrid Enabling Reversible and Enhanced Self-Trapped Exciton Emission under High Pressure.

Zero-dimensional organic-inorganic metal halide hybrids provide ideal bulk-crystal platforms for exploring the pressure engineering of electron-phonon coupling (EPC) and self-trapped exciton (STE) emission at the molecular level. However, the low stiffness of inorganic clusters hinders the reversible tuning of these physical properties. Herein, we designed a Sb3+-doped metal halide with a high emission yield (89.4%) and high bulk modulus (35 GPa) that enables reversible and enhanced STE emission (20-fold) under pressure. The high lattice rigidity originates from the corner-shared cage-structured inorganic tetramers and ring-shaped organic ligands. Further, we reveal that the pressure-enhanced emission regime below 4.5 GPa is owing to the lattice hardening and preferably EPC strength reducing, while the pressure-insensitive emission regime within 4.5-8.5 GPa results from the enhanced intercluster Coulombic attraction force that resists intracluster compression. These results provide insights into the structure-property relation and molecular engineering of zero-dimensional metal halides toward wide-band and pressure-sensitive light sources.

Optical polarization properties of TPP2MnBr4 perovskite crystal adjusted by the self-trapping state.

Low-dimensional networked organic-inorganic hybrid metal halide crystal has become an emerging hotspot material due to its opportunities and advantages in the development of white-light-emitting diodes. Therefore, its photoluminescence (PL) mechanism is important. Herein, we study the PL behavior of columniform TPP2MnBr4 crystals using multi-spectroscopy. The temperature-dependent PL data show that the PL of the TPP2MnBr4 crystal originates from the recombination of a self-trapping exciton. A polarization-dependent PL test suggests that the self-trapping exciton is anisotropic, which indicates that the distribution of self-trapping states is sensitive to the orientation of the crystal axis. Space-resolved PL spectroscopy shows that the anisotropy of PL gradually weakens along the orientation of the columniform crystal, which has a longer relaxation distance than traditional light-wave-guiding behavior. Thus, anisotropy of PL can exist before it disappears in the crystal. Our results elucidate the PL mechanism of low-dimensional networked organic-inorganic hybrid metal halide crystals and provide a foundation for advanced optical polarization devices based on them.

One-Dimensional Organic-Inorganic Lead Bromide Hybrids with Excitation-Dependent White-Light Emission Templated by Pyridinium Derivatives.

Organic-inorganic hybrid metal halides have attracted widespread attention due to their excellent tunability and versatility. Here, we have selected pyridinium derivatives with different substituent groups or substitution positions as the organic templating cations and obtained six 1D chain-like structures. They are divided into three types: type I (single chain), type II (double chain), and type III (triple chain), with tunable optical band gaps and emission properties. Among them, only (2,4-LD)PbBr3 (2,4-LD = 2,4-lutidine) shows an exciton-dependent emission phenomenon, ranging from strong yellow-white to weak red-white light. By comparing its photoluminescence spectrum with that of its bromate (2,4-LD)Br, it is found that the strong yellow-white emission at 534 nm mainly came from the organic component. Furthermore, through a comparison of the fluorescence spectra and lifetimes of (2,4-LD)PbBr3 and (2-MP)PbBr3 (2-MP = 2-methylpyridine) with similar structures at different temperatures, we confirm that the tunable emission of (2,4-LD)PbBr3 comes from different photoluminescent sources corresponding to organic cations and self-trapped excitons. Density functional theory calculations further reveal that (2,4-LD)PbBr3 has a stronger interaction between organic and inorganic components compared to (2-MP)PbBr3. This work highlights the importance of organic templating cations in hybrid metal halides and the new functionalities associated with them.

A novel strategy for enhancing NO2 sensitivity of new 1D organic–inorganic metal halide hybrids

A novel strategy for enhancing NO2 sensitivity of new 1D organic–inorganic metal halide hybrids

Manganese‐Halide Single‐Crystal Scintillator Toward High‐Performance X‐Ray Detection and Imaging: Influences of Halogen and Thickness

AbstractScintillators, which can convert high‐energy ionizing radiation (e.g., X‐ or γ‐rays) into ultraviolet‐visible light, have been widely applied in medical and industrial fields. Developing new scintillation materials with high performance and low cost is very desirable in order to address the growing application demands. Among them, single‐crystal scintillators of organic‐inorganic hybrid metal halides (OIMHs) have attracted much attention because of their excellent optical transparency, suppressed light scattering, and facile solution preparation methods. Herein, three new centimeter‐sized (2‐DMAP)2MnX4 (2‐DMAP+ = 2‐dimethylaminopyridinium, X = Cl, Br, I) single crystals with high crystal quality are synthesized via the solvent evaporation method. Benefiting from the high optical transparency and remarkable luminescence property, (2‐DMAP)2MnBr4 delivers a high X‐ray light yield of 22 000 photons MeV−1, a low limit of detection of 9.50 nGy s−1, and an excellent X‐ray imaging spatial resolution of 20–25 lp mm−1. Moreover, the regulation of single‐crystal thickness from 0.31 mm to 3.03 mm can be easily achieved via a simple solution post‐treatment method, which has a significant influence on the transmittance, spatial imaging resolution, and detection limit. This work demonstrates a promising single‐crystal scintillator for the application of high‐resolution X‐ray imaging with low preparation cost and tunable thickness.

Iminophenol as a ligand or cation in cobalt(II and II,III) complexes: synthetic approaches, spectral and structural studies

New complexes [H2L]2CoCl4 (І) and [CoІІCоІІІCl2L3]H2O (ІІ), where HL is a condensation product of o-vanillin and methylamine, were synthesized and characterized by IR, UV/Vis spectroscopies, and X-ray structural analysis. For the synthesis of I, cobalt (II) chloride was used as a metal source, while for II, cobalt powder and its salt were used simultaneously. In the preparation of I, the use of methylamine hydrochloride contributed to the formation of tetrachlorocobaltate(II) with the protonated Schiff base H2L+as a cation. The monovalent cations are almost planar and show the presence of intramolecular O/N–HО hydrogen bonds. In the crystal, columns of cations connected by - stacking alternate with double-row columns of tetrahedral [CoCl4]2– anions and are additionally joined by a branched system of O/N–HCl hydrogen bonds. Crystal II is built of neutral molecules CoІІСоІІІCl2L3 and uncoordinated water molecules. In the molecule, the main CoІІІL3 fragment with a metal atom in the octahedral environment of three deprotonated ligands attaches a cobalt(II) atom at the CoIICoIII distance of 3.17 Å. The cobalt(II) atom has a highly distorted five-coordinate СоІІО3Cl2 environment formed by two bridging oxygen atoms of deprotonated phenoxy groups, the O atom of the methoxy group of the ligands, and two chlorine atoms. The obtained results allow us to propose the use of the metal salt+its powder combination for the purposeful synthesis of mixed-valent complexes of metals capable of exhibiting various oxidation states. Deliberate protonation of the Schiff base can be used to prepare organic-inorganic metal halide hybrids with functionalized cations.

Tunable Afterglow and Self-Trapped Exciton Emissions in Zr (IV)-Based Organic-Inorganic Metal Halide Hybrids by Metal-Ion Doping.

Low-dimensional hybrid metal halide (LDHMH) materials have attracted considerable attention owing to their intriguing optical properties. To the best of the knowledge, this is the first study to successfully demonstrate both self-trap exciton (STE) and afterglow emissions in Zr-based LDHMH materials. The obtained pure (Ph3 S)2 ZrCl6 crystals showed near-ultraviolet phosphorescence and a green afterglow owing to the organic cation Ph3 S+ , while the Bi-doped and Sb-doped crystals exhibited both STE and afterglow emissions. However, the Te-doped crystals showed only a broad yellow STE emission owing to the [TeCl6 ]2- octahedron. In addition, all the crystals showed good stability. Notably, Sb-doped crystals produced white light, which can be adjusted between cold white and warm white using different excitations. Finally, this strategy for both STE and afterglow emissions can be applied to other LDHMH materials for optical applications.

Synthesizing and characterization of Lead Halide Perovskite Nanocrystals solar cells from reused car batteries

With the rapid increase of efficiency up to 23.7% during the past few years, hybrid organic-inorganic metal halide perovskite solar cells (PSCs) have become a research “hot spot” for many solar cell researchers. The perovskite materials show various advantages due to unique characteristics of perovskite materials, such as high photo-to-electric conversion efficiency, direct band gap, high light absorption coefficient, high charge-carrier mobility and long electron-hole electron transport distance. The low-cost fabrication techniques together with the high efficiency makes PSCs comparable with Si-based solar cells. This paper begins with the discussion of crystal structures of perovskite based on recent research findings. The following part of this paper discussion of synthetic process of lead iodide perovskite materials from lead-acid battery and Harvesting material from the anodes and cathodes of car battery; synthesizing PbI2 from the collected materials and compare with pure Lead iodide to know the absolute by XRD peak, depositing lead iodide perovskite nanocrystals. Efficient flexible PSCs are fabricated onto FTO glass substrate by a two-step coating method under ambient condition. By adjusting the concentration of precursor CH3NH3I (MAI), the morphology and thickness of perovskite layer is effectively tailored, according to SEM analysis and using TiO2 as electron transport layer instead of ZnO and CuI instead of spiro-OMeTAD as hole transport layer.

Achieving a Highly Stable Perovskite Photodetector with a Long Lifetime Fabricated via an All-Vacuum Deposition Process

Hybrid organic-inorganic metal halide perovskites (HOIP) have become a promising visible light sensing material due to their excellent optoelectronic characteristics. Despite the superiority, overcoming the stability issue for commercialization remains a challenge. Herein, an extremely stable photodetector was demonstrated and fabricated with Cs0.06FA0.94Pb(I0.68Br0.32)3 perovskite by an all-vacuum process. The photodetector achieves a current density up to 1.793 × 10-2 A cm-2 under standard one sun solar illumination while maintaining a current density as low as 8.627 × 10-10 A cm-2 at zero bias voltage. The linear dynamic range (LDR) and transient voltage response were found to be comparable to the silicon-based photodetector (Newport 818-SL). Most importantly, the device maintains 95% of the initial performance after 960 h of incessant exposure under one sun solar illumination. The achievements of these outstanding results contributed to the all-vacuum deposition process delivering a film with high stability and good uniformity, which in turn delays the degradation process. The degradation mechanism is further investigated by impedance spectroscopy to reveal the charge dynamics in the photodetector under different exposure times.

Implications of Electron Transport Layer and Back Metal Contact Variations in Tin–Lead Perovskite Solar Cells Assessed by Spectroscopic Ellipsometry and External Quantum Efficiency

The structural and optical properties of hybrid organic-inorganic metal halide perovskite solar cells are measured by spectroscopic ellipsometry to reveal an optically distinct interfacial layer among the back contact metal, charge transport, and absorber layers. Understanding how this interfacial layer impacts performance is essential for developing higher performing solar cells. This interfacial layer is modeled by Bruggeman effective medium approximations (EMAs) to contain perovskite, C60, BCP, and metal. External quantum efficiency (EQE) simulations that consider scattering, electronic losses, and the formation of nonparallel interfaces are created with input derived from ellipsometry structural-optical models and compared with experimental EQE to estimate optical losses. This nonplanar interface causes optical losses in short circuit current density (JSC) of up to 1.2 mA cm-2. A study of glass/C60/SnO2/Ag or Cu and glass/C60/BCP/Ag film stacks shows that C60 and BCP mix, but replacing BCP with SnO2 can prevent mixing between the ETLs to prevent contact between C60 and back contact metal and enable the formation of a planar interface between ETLs and back contact metals.

Intermolecular arrangement facilitated broadband blue emission in group-12 metal (Zn, Cd) hybrid halides and their applications

Various fluorescent organic materials are widely known for their potential applications in light-emitting diodes, organic lasers, anti-counterfeiting and bio-imaging. However, poor emission efficiency and stability issues limit their usability. Here we report the syntheses, crystal and electronic structures, and optical characterizations of two new hybrid organic-inorganic group 12 halides, (P-xd)ZnCl4 and (P-xd)CdCl4 (where (P-xd) = p-xylylenediammonium). Single crystals of both compounds can be conveniently synthesized by solution chemistry methods from their low-cost, low toxicity and easily available precursors. (P-xd)ZnCl4 possesses a crystal structure featuring alternating layers of organic cations and completely separated anionic [ZnCl4]2- tetrahedral units of zero-dimensional (0D) connectivity. In contrast, (P-xd)CdCl4 adopts similar layering of organic cations sandwiched between perovskite sheets of two-dimensional (2D) connectivity, which are formed by corner-sharing anionic [CdCl6]4- octahedral units. The structural, optical, and electronic studies suggest that the incorporation of organic and inorganic structural units into a hybrid structure improves its blue emission efficiency with nearly 23 times and 4 times higher photoluminescence quantum yield (PLQY) values in (P-xd)ZnCl4 and (P-xd)CdCl4, respectively, as compared to the organic precursor. Notably, PLQY of 23% for (P-xd)ZnCl4 is the highest reported to date for Zn-based hybrid organic-inorganic metal halides, where emission originates from the organic component. Both (P-xd)ZnCl4 and (P-xd)CdCl4 demonstrate considerably improved air-, thermal- and photostability, which suggest their suitability for potential practical applications such as fingerprint detection and solid-state lighting.

One-Dimensional Chiral Copper Iodide Chain-Like Structure Cu4 I4 (R/S-3-quinuclidinol)3 with Near-Unity Photoluminescence Quantum Yield and Efficient Circularly Polarized Luminescence.

Chiral organic-inorganic hybrid metal halide materials have shown great potential for circularly polarized luminescence (CPL) related applications for their tunable structures and efficient emissions. Here, this work combines the highly emissive Cu4 I4 cubane cluster with chiral organic ligand R/S-3-quinuclidinol, to construct a new type of 1D Cu-I chains, namely Cu4 I4 (R/S-3-quinuclidinol)3 , crystallizing in noncentrosymmetric monoclinic P21 space group. These enantiomorphic hybrids exhibit long-term stability and show bright yellow emission with a photoluminescence quantum yield (PLQY) close to 100%. Due to the successful chirality transfer from the chiral ligands to the inorganic backbone, the enantiomers show intriguing chiroptical properties, such as circular dichroism (CD) and CPL. The CPL dissymmetry factor (glum ) is measured to be ≈4×10-3 . Time-resolved photoluminescence (PL) measurements show long averaged decay lifetime up to 10 µs. The structural details within the Cu4 I4 reveal the chiral nature of these basic building units, which are significantly different than in the achiral case. This discovery provides new structural insights for the design of high performance CPL materials and their applications in light emitting devices.

Organic–Inorganic Hybrid Alkali Copper Iodides for Bright Emission across the Visible Spectrum

Organic–inorganic hybrid metal halides are well known for their structural flexibility and high photoluminescence quantum yield (PLQY), showing great potential for optical applications. In this work, we demonstrate the synthesis of a series of alkali copper(I) iodide (ACuI)-based (A = Na, K, Rb, and Cs) organic–inorganic hybrid materials with different structures and emission peaks by adjustment of the alkali atoms and organic molecules. These compounds possess strong PL with emission peaks in the range of 530–660 nm, the highest PLQY of 91% was achieved for KCuI2(C4H8OS)2, and their different emissions originate from distinct charge-transfer processes. Green, yellow, and red light-emitting diodes (LEDs) can be fabricated by using these materials, and a white LED based on all-copper iodide phosphors is demonstrated with a high color rendering index of 93 by utilizing a mixture of blue-emissive Cs3Cu2I5 and yellow-emissive Rb2Cu2I4(C4H8OS)3 powders. This work provides a new strategy for the development of hybrid copper halides with composition-tunable structures and high performance and demonstrates that this series of (ACuI)-based compounds could be candidates for emission applications, including lighting or display.

Moisture-Induced reversible structure conversion of Zero-Dimensional organic cuprous bromide hybrids for multiple photoluminescent anti-Counterfeiting, information encryption and rewritable luminescent paper

With social development and the technology advancement, the demand for high-security photoluminescence (PL) anti-counterfeiting and information encryption materials is increasing constantly. Herein, two organic cuprous bromide hybrids, namely (TPA)CuBr2 and (TPA)2Cu4Br6, with variable coordination geometries were synthesized via a facile solution method. (TPA)CuBr2 shines bright cyan emission with a photoluminescence quantum efficiency (PLQE) of 81 % under 254 nm excitation, while (TPA)2Cu4Br6 exhibits orange emission with a PLQE of 95 % upon 365 nm irradiation. Interestingly, a reversible structural conversion could be triggered by water or heat between (TPA)CuBr2 and (TPA)2Cu4Br6, accompanied by a back-and-forth emission color change between cyan and orange under its respective excitation. The emission mechanism of above two compounds was investigated, and the results show that they stem from self-trapped excitons emission. Such PL color switching under the external stimuli of water, heat and different excitation wavelengths enables us to construct a series of anti-counterfeiting and information encryption scenarios. In addition, the rewritable PL paper based on (TPA)CuBr2 with water as ink is realized. These two compounds not only provide a good way to modulate zero-dimensional Cu(I)-based metal halide with highly efficient emission, but also a new example to develop multifunctional applications by organic–inorganic hybrid metal halides.

(C5N2H14)GeBr4: A 2D Organic Germanium Bromide Perovskite with Strong Orange Photoluminescence Properties

Hybrid organic-inorganic metal halide (OIMH) perovskites are regarded as potential photoluminescent (PL) materials and have attracted intensive attention. Here, we select 1-methylpiperazine as an organic component and successfully obtain a two-dimensional (2D) Ge-based OIMH perovskite, (1-mpz)GeBr4. It features a 2D layered structure composed of distorted [GeBr6]4- octahedra with organic (C5H14N2)2+ located between the layers. (1-mpz)GeBr4 exhibits strong orange color under ultraviolet (UV) light and possesses good PL stability for over 2 months. The photoluminescence quantum efficiency is measured to be 7.15% at room temperature, which is the largest among all reported low-dimensional Ge-based perovskites. Experimental measurements, combined with first-principles calculations, reveal that its PL property is attributed to self-trapped excitons (STEs) from [GeBr6]4- groups. From the deduced structure-property relationship, Ge-based OIMH PL perovskites with good stability and high PL efficiency can be expected.