Inorg. Chem. 2023, 62, 31, 12501–12509.https://doi.org/10.1021/acs.inorgchem.3c01726

Organic–inorganic metal halides (OIMHs) have various crystal structures and offer excellent semiconducting properties. Here, we report three novel OIMHs, (PPA)₆InBr₉ (PPA = [C₆H₅(CH₂)₃NH₃]⁺), (PBA)₂SbBr₅, and (PBA)₂SbI₆ (PBA = [C₆H₅(CH₂)₄NH₃]⁺), showing typical zero-dimensional (0D) structure, octahedra dimers, and corner-sharing one-dimensional chains and crystallized in the monoclinic system with P2₁, P2₁/c, and C2/c space groups, respectively. (PPA)₆InBr₉, (PBA)₂SbBr₅, and (PBA)₂SbI₆ have experimental optical band gaps of ∼3.16, ∼2.24, and 1.48 eV, respectively. (PPA)₆InBr₉ exhibits bright-orange light emission centered at 642 nm with a full-width at half-maximum of 179 nm (0.51 eV) and a Stokes shift of 277 nm (1.46 eV). After Sb³⁺ doping, the peak position did not change, and the photoluminescence quantum yield increased significantly from 9.2 to 53.0%. The efficient emission of Sb:(PPA)₆InBr₉ stems from the isolated ns² luminescent center and strong electron–phonon coupling, making the spin-forbidden ³P₁–¹S₀ observable. By combining commercial blue and green phosphors with orange-red-light-emitting (PPA)₆In_0.99Sb_0.01Br₉, a white-light-emitting diode was constructed, with the color-rendering index reaching up to 92.3. Our work highlights three novel 0D OIMHs, with chemical doping of Sb³⁺ shown to significantly enhance the luminescence properties, demonstrating their potential applications in solid-state lighting.

J. Mater. Chem. C, 2022,10, 9841-9848.https://doi.org/10.1039/D2TC01672A

As an emerging material, organic–inorganic metal halides (OIMHs) have been widely studied in the field of optoelectronics in recent years. In this work, a series of compounds (TMEDA)₃(Sb_xBi_1−x)₂Cl₁₂·H₂O (0.1 ≤ x ≤ 0.6) (TMEDA = N,N,N′-trimethylethylenediamine) were synthesized. The incorporation of Sb³⁺ greatly enhanced the photoluminescence quantum yield of (TMEDA)₃Bi₂Cl₁₂·H₂O from 1% to 38%. The variation in the degree of distortion of the inorganic octahedra and the relatively suitable distances between metal ions are considered to be the reasons for the intense emission. (TMEDA)₃(Sb_xBi_1−x)₂Cl₁₂·H₂O (0.1 ≤ x ≤ 0.6) exhibited a yellow phosphorescence emission at 605 nm and 595 nm under excitation at 305 nm and 375 nm, respectively. With the incorporation of Sb³⁺, changes in the emission intensity under different excitation wavelengths showed different trends. Thus, we attribute the yellow broadband emissions to the triplet emission of Bi³⁺ and Sb³⁺. Finally, we combined (TMEDA)₃(Sb_0.5Bi_0.5)₂Cl₁₂·H₂O with commercial phosphors and a near-ultraviolet light-emitting diode chip to prepare a white-light-emitting diode device, which exhibited a high color-rendering index of 94.4. The aim of our work was to investigate the structural effects of the photoluminescence of Sb³⁺-doped OIMHs and to further explore ways to improve the Sb³⁺ emission efficiency in the field of photoluminescence of OIMHs.

J. Mater. Chem. C, 2022,10, 13137-13142.https://doi.org/10.1039/D2TC02838G

Low-dimensional organic–inorganic metal halides with broad light emission have drawn widespread attention, however, the low thermal stability has been a major obstacle to their commercialization. Herein, zero-dimensional (C₉H₁₅N₃)ZnCl₄ with space group P2₁ was synthesized for the first time. (C₉H₁₅N₃)ZnCl₄ emits blue fluorescence at room temperature with external quantum efficiency as high as 42.5%, which are among the highest reported for Zn-based OIMHs, and it is comparable with the commercialized phosphors. Notably, the luminous integral intensity of (C₉H₁₅N₃)ZnCl₄ at 470 K remains more than 50% of that at room temperature. Mn²⁺ doping of (C₉H₁₅N₃)ZnCl₄ was conducted to improve the photoluminescence. With increasing Mn²⁺ concentration, the title compounds underwent fluorescence conversion from blue to green. The external quantum efficiencies of (C₉H₁₅N₃)ZnCl₄ : 5%Mn²⁺ and (C₉H₁₅N₃)ZnCl₄ : 50%Mn²⁺ were 43.7% and 42.9%, respectively. More importantly, (C₉H₁₅N₃)ZnCl₄ : 5%Mn²⁺ exhibited different luminous colors at different temperatures. As the temperature decreased from 290 to 110 K, the luminous color changed from green to light blue. Finally, a composite film was prepared to demonstrate the temperature response of this material, and the absolute sensitivity reaches 0.57%/K. These findings fill in the gaps for low-temperature indication and expand the application scenarios of OIMHs.

ACS Appl. Electron. Mater. 2022, 4, 4068−4076.https://doi.org/10.1021/acsaelm.2c00705

Phosphors with narrow-band emission are in great demand for liquid crystal display backlighting applications. In this work, four zero-dimensional Mn²⁺-based organic–inorganic metal halides (OIMHs), (C₁₃H₂₆N)₃MnBr₄·Br, (C₁₃H₂₆N)₂MnCl₄, and (C₇H₁₈N)₂MnX₄ (X = Cl, Br), were synthesized, and their crystal structures were solved. Under blue-light excitation, all of the materials exhibited bright narrow-band green luminescence centered at 515–525 nm with high photoluminescence quantum yields (PLQYs). Significantly, (C₁₃H₂₆N)₃MnBr₄·Br and (C₁₃H₂₆N)₂MnCl₄ exhibited small full width at half-maximum (FWHM) values of 43 and 48 nm with PLQYs of 77.8 and 79.3% at room temperature, respectively. Compared with the reported luminescent OIMHs, ultrahigh thermal quenching temperatures were observed, and at 420 K, emission intensities of (C₁₃H₂₆N)₃MnBr₄·Br and (C₁₃H₂₆N)₂MnCl₄, remained 82.7 and 64.2% of those at room temperature, respectively. The rigid environment provided by the C₁₃H₂₆N⁺ cation has a strong confinement effect on the [MnX₄]^2– tetrahedra, leading to a narrower FWHM and higher thermal quenching temperature. Finally, (C₁₃H₂₆N)₃MnBr₄·Br was combined with commercial phosphors to fabricate light-emitting diodes (LEDs) with a wide color gamut of up to 113% NTSC (National Television System Committee). This work provides a reference for designing the OIMHs for liquid crystal display LEDs by tuning the organic cations.

Journal of Alloys and Compounds Volume 960, 15 October 2023, 170895, https://doi.org/10.1016/j.jallcom.2023.170895

Pavonite homologues are semiconductors that show potential for thermoelectric applications. Herein, we report the synthesis of a quaternary selenide, In_0.5Mn₂Bi_3.5Se₈, that exhibits good thermal stability below 1032 K. Whereas most pavonite compounds exhibit the metallic properties of degenerate semiconductors, In_0.45Mn_2.17Bi_3.38Se₈ possesses a band gap of 0.85 eV. In addition, its electrical conductivity and Seebeck coefficient exceed 3 S/cm and 300 μV/K at 810 K, respectively, with the compound mainly displaying semiconductor properties. In_0.45Mn_2.17Bi_3.38Se₈ exhibits paramagnetism at room temperature followed by a paramagnetic-to-antiferromagnetic transition at ∼10.2 K. Our findings enrich the current understanding of the pavonite homologous series, providing useful insight for future exploration in related fields.

ADVANCED OPTICAL MATERIALS, 2023-02-04, https://doi.org/10.1002/adom.202202304

Efficient broadband emitting organic–inorganic metal hybrids (OIMHs) have attracted great attention recently as promising single-component white light emitters. Here a new zero-dimensional (0D) OIMH (C₁₃H₁₄N)₂InCl₅ (C₁₃H₁₄N⁺ = N-methyldiphenylammonium) is reported, which features unique five-coordinated [InCl₅]²⁻ trigonal bipyramid motif. For the first time, it is demonstrated that the trigonal bipyramid units in 0D OIMH can act as luminescence centers, showing blue emission under UV light. Remarkably, incorporating Sb³⁺ in [InCl₅]²⁻ trigonal bipyramids induces a new dual-band emission at 540 and 735 nm resulting from the singlet and triplet self-trapped excitons in [SbCl₅]²⁻, leading to complete coverage of the entire visible spectrum. The resulting emissions in (C₁₃H₁₄N)₂InCl₅:Sb³⁺ are tunable from cold to warm white with the correlated color temperatures changing from 5574 to 3473 K and more importantly, an ultra-high color rendering index (CRI) up to 96 being observed, which is comparable to the highest value in hybrid metal halides. A high photoluminescence quantum yield of 46.26% is simultaneously obtained in this system. This work demonstrates that the 0D OIMH with trigonal bipyramid motif is an excellent system for realizing the single-component white light emission with both high efficiency and ultra-high CRI.

Adv. Funct. Mater., 2022, 32, 13, 2110771. https://doi.org/10.1002/adfm.202110771

Stimulus-responsive photoluminescent materials have attracted extensive research attention in recent years owing to their potential application in information storage and switch devices. It is important to further explore such bistable materials as well as the underlying transformation mechanisms. Herein, the syntheses and mechanically tunable “on–off” photoluminescence (PL) of two organic–inorganic hybrid metal halides, (Bmpip)₉Pb₃Zn₂Br₁₉ and (Bmpip)₉Pb₃Cd₂Br₁₉ (Bmpip⁺ = 1-butyl-1-methyl-piperidinium, C₁₀H₂₂N⁺), are reported. Both as-obtained compounds are nonemissive under UV light at ambient conditions but exhibit bright PL upon grinding or under hydrostatic pressure. Interestingly, the PL is quenchable by short-time annealing or storage in air for 1 week, and the process is repeatable. Through a combination of extensive structural and spectral analyses, the crucial role of the organic cations interacting with inorganic chromophores in the “on–off” PL behavior of the title compounds is revealed. Moreover, pressure-induced PL and PL-enhancement phenomena are observed in both compounds, which are similar to but slightly different than the above-mentioned mechano-PL. Finally, proof-of-concept devices are fabricated to demonstrate the potential applications of the title compounds in message recording and force sensing.

Inorg. Chem. 2022, 61, 19, 7560–7567. https://doi.org/10.1021/acs.inorgchem.2c00711

Organic–inorganic metal halides (OIMHs) exhibit excellent photoelectric properties; however, their high-temperature light-emission stability requires further improvement. Here, we report three isostructural OIMHs (C₂H₈N)₄InCl₇, (C₂H₈N)₄SbCl₇, and (C₂H₈N)₄SbBr₇ (C₂H₈N⁺ = dimethylammonium). They are all crystallized in the P2₁2₁2 space group with a zero-dimensional (0D) structure, with orange-red photoluminescence (PL) under 365 nm UV excitation. Among them, (C₂H₈N)₄InCl₇ exhibits the strongest PL with a photoluminescence quantum yield (PLQY) of 13.9% at room temperature. Optical property measurements and density functional theory unveil that the luminescence of (C₂H₈N)₄InCl₇ at 405 and 620 nm is due to free exciton and self-trapped exciton emission, respectively. It is worth noting that (C₂H₈N)₄InCl₇ shows a high PL quenching temperature, maintaining 50% of its room-temperature PL intensity at 425 K, which is rare in OIHMs. This is much higher than the application temperature of phosphors in practical solid-state lighting applications (363–383 K). In this temperature range, the luminous intensity of (C₂H₈N)₄InCl₇ exceeds 60% of that at room temperature. The high PL quenching temperature observed in (C₂H₈N)₄InCl₇ indicates the potential of OIMHs for applications in phosphor-converted light-emitting diodes.