Three new lead-free organic–inorganic metal halides (OIMHs) (C7H8N3)3InX6·H2O (X = Cl, Br) and (C7H8N3)2SbBr5 were synthesized. First-principles calculations indicate that the highest occupied molecular orbitals (HOMOs) of the two In-based OIMHs are constituted of π orbitals from [C7H8N3]+ spacers. (C7H8N3)3InX6·H2O (X = Cl, Br) shows an indirect optical gap, which may result from this organic-contributed band edge. Despite the indirect-gap nature with extra phonon process during absorption, the photoluminescence of (C7H8N3)3InBr6·H2O can still be significantly enhanced through Sb doping, with the internal photoluminescence quantum yields (PLQY) increased 10-fold from 5% to 52%. A white light-emitting diode (WLED) was fabricated based on (C7H8N3)3InBr6·H2O:Sb3+, exhibiting a high color-rendering index of 90. Our work provides new systems to deeply understand the principles for organic spacer choice to obtain the 0D metal OIMHs with specific band structure and also the significant enhancement of luminescence performance by chemical doping.

We report a new 0D lead-free halide with both [InBr6]3− octahedra and [InBr4]− tetrahedra as inorganic units. High-efficiency red photoluminescence can be achieved via Sb doping in this emissive material with a PLQY of 61%.

Organic−inorganic hybrid metal halides have attracted widespread attention as emerging optoelectronic materials, especially in solid-state lighting, where they can be used as single-component white-light phosphors for white light-emitting diodes. Herein, we have successfully synthesized a zero-dimensional (0D) organic−inorganic hybrid mixed-metal halide (Bmpip) 2 Pb x Sn 1−x Br 4 (0 < x < 1, Bmpip + = 1-butyl-1-methyl-piperidinium, C 10 H 22 N + ) that crystallizes in a monoclinic system in the C2/c space group. Pb 2+ and Sn 2+ form a four-coordinate seesaw structure separated by organic cations forming a 0D structure. For different excitation wavelengths, (Bmpip) 2 Pb x Sn 1−x Br 4 (0 < x < 1) exhibits double-peaked emission at 470 and 670 nm. The emission color of (Bmpip) 2 Pb x Sn 1−x Br 4 can be easily tuned from orange-red to blue by adjusting the Pb/Sn molar ratio or excitation wavelength. Representatively, (Bmpip) 2 Pb 0.16 Sn 0.84 Br 4 exhibits approximately white-light emission with high photoluminescence quantum yield up to 39%. Interestingly, the color of (Bmpip) 2 Pb x Sn 1−x Br 4 can also be easily tuned by temperature, promising its potential for application in temperature measurement and indication. Phosphor-converted light-emitting diodes are fabricated by combining (Bmpip) 2 Pb x Sn 1−x Br 4 and 365 nm near-UV LED chips and exhibit high-quality light output.

Organic−inorganic metal halides (OIMHs) have various crystal structures and offer excellent semiconducting properties. Here, we report three novel OIMHs, (PPA) 6 InBr 9 (PPA = [C 6 H 5 (CH 2 ) 3 NH 3 ] + ), (PBA) 2 SbBr 5 , and (PBA) 2 SbI 6 (PBA = [C 6 H 5 (CH 2 ) 4 NH 3 ] + ), showing typical zero-dimensional (0D) structure, octahedra dimers, and corner-sharing one-dimensional chains and crystallized in the monoclinic system with P2 1 , P2 1 /c, and C2/c space groups, respectively. (PPA) 6 InBr 9 , (PBA) 2 SbBr 5 , and (PBA) 2 SbI 6 have experimental optical band gaps of ∼3.16, ∼2.24, and 1.48 eV, respectively. (PPA) 6 InBr 9 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 Sb 3+ 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) 6 InBr 9 stems from the isolated ns 2 luminescent center and strong electron−phonon coupling, making the spin-forbidden 3 P 1 − 1 S 0 observable. By combining commercial blue and green phosphors with orange-red-light-emitting (PPA) 6 In 0.99 Sb 0.01 Br 9 , 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 Sb 3+ shown to significantly enhance the luminescence properties, demonstrating their potential applications in solid-state lighting.

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.