Phosphors with narrow-band emission are in great demand for liquid crystal display backlighting applications. In this work, four zero-dimensional Mn 2+ -based organic−inorganic metal halides (OIMHs), (C 13 H 26 N) 3 MnBr 4 •Br, (C 13 H 26 N) 2 MnCl 4 , and (C 7 H 18 N) 2 MnX 4 (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, (C 13 H 26 N) 3 MnBr 4 •Br and (C 13 H 26 N) 2 MnCl 4 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 (C 13 H 26 N) 3 MnBr 4 •Br and (C 13 H 26 N) 2 MnCl 4 , remained 82.7 and 64.2% of those at room temperature, respectively. The rigid environment provided by the C 13 H 26 N + cation has a strong confinement effect on the [MnX 4 ] 2− tetrahedra, leading to a narrower FWHM and higher thermal quenching temperature. Finally, (C 13 H 26 N) 3 MnBr 4 •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.

Organic–inorganic metal halides (OIMHs) with unique structural flexibility possess excellent photoelectric properties. They are regarded as next‐generation photovoltaic materials, phosphors, semiconductors, and ferroelectrics. The metal‐halide units in OIMHs are good microscopic building blocks of nonlinear optical crystals for laser wavelength conversion. However, most OIMHs are absent from nonlinear optics owing to their macroscopic nonlinear optical (NLO)‐inactive centrosymmetric crystal structure. In this study, two new lead‐free OIMHs, (TMEDA)SbI5 and (TMEDA)BiI5 (where TMEDA2+ is N,N,N′‐trimethylethylenediammonium), having 1D structure, crystallized in the orthorhombic system with a non‐centrosymmetric P212121 space group, are synthesized. Remarkably, upon 2090 nm laser irradiation, both compounds possess a strong infrared (IR) nonlinear optical response of the same magnitude as AgGaS2, which is a benchmark semiconductor‐type nonlinear optical crystal. In addition, under the excitation of ultraviolet and visible lights, both compounds produce self‐trapped exciton‐induced red‐light emission. First‐principles electronic structure calculations reveal that the optical properties originate from the electronic transitions within the inorganic metal‐halide group. The obtained results indicate that both compounds are potential photoelectric materials for laser frequency conversion and fluorescence, and the observation of NLO effect in these two compounds verifies that OIMHs are also good candidates for NLO crystals.

The participation of organic cations plays an important role in tuning broad-spectra emissions. Herein, we synthesized a series of Mn(II)-based two-dimensional (2D) halide perovskites with arylamine cations of different lengths having the general formula (C 6 H 5 (CH 2 ) x NH 3 ) 2 MnCl 4 (x = 1−4), with the x = 4 compound reported here for the first time. With the increase in the −(CH 2 )− in organic cations, the distance between adjacent inorganic layers increases, causing the title compounds to exhibit different structural distortions. As the Mn−Cl−Mn angular distortion increases, the experimental optical band gaps of the title compounds increase correspondingly. When the angle distortion between the octahedrons of the compounds is similar, the band gaps may also be affected by the distortion of the octahedron itself (the bond-length distortion of 2 is greater than that of 4). Under UV-light irradiation at 298 K, all of the compounds exhibit two emission peaks centered at 480−505 and 610 nm, corresponding to the organic-cation emission and the 4 T 1 (G) to 6 A 1 (S) radiative transition of Mn 2+ ions, respectively. Among these title compounds, (PPA) 2 MnCl 4 [(PPA) + = C 6 H 5 (CH 2 ) 3 NH 3 + ] exhibits the strongest photoluminescence (PL). The study of the title compounds contributes to an in-depth understanding of the relationship between the structural distortion and optical properties of 2D Mn(II)-based perovskite materials.

In-based organic−inorganic metal halides (OIMHs) have received growing interest in recent years as promising luminescent materials. However, the high efficiencies of 0D In-based OIMHs are all dependent on Sb doping in the existing literature. Here, we report a novel 0D In-based OIMH (C 10 H 22 N 2 ) 2 In 2 Br 10 , which exhibits intrinsic broadband emission (610 nm), and the photoluminescence quantum yield (PLQY) can reach 70% without Sb doping. (C 10 H 22 N 2 ) 2 In 2 Br 10 shows a typical 0D structure with three different In−Br polyhedra (two octahedra and one tetrahedron) separated by large organic cations. Based on the optical property measurements and theoretical calculations, we demonstrate that (C 10 H 22 N 2 ) 2 In 2 Br 10 is an indirect semiconductor with a band gap of 3.74 eV, and the In−Br inorganic moiety is primarily responsible for the intense emission of (C 10 H 22 N 2 ) 2 In 2 Br 10 . Interestingly, the unique double octahedral configuration in (C 10 H 22 N 2 ) 2 In 2 Br 10 may enhance the structural distortion and stimulate the self-trapped excitons (STEs), leading to the related high PLQY. Our work provides a novel 0D In-based OIMH with high-efficiency intrinsic emission, which is helpful for understanding the structure−PL relationships of hybrid halides.

Exploration of Sn4+-based organic–inorganic metal halides and suggests an efficient lone-pair-containing cation doping route to enhance the luminescent performance.