Zero-Dimensional Halides with ns² Electron (Sb³⁺) Activation to Generate Broad Photoluminescence

Abstract

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.

Excited State Regulated Emission in Hybrid Indium Halides via Crystal Structure Switch

“…Tauc diagram analysis showed that the band gap of undoped sample PA 6 InCl 9 was 4.91 eV, and the band gap of PA 4 NaInCl 8 was 4.86 eV. With the introduction of Sb 3+ , the value of the band gap decreases from 4.82 and 4.80 eV to 4.71 and 4.70 eV with increasing doping concentration, respectively (Figure S8), which was consistent with previous reports. − …”

“…However, indium-based halide perovskites have poor absorption capacity. To address this issue, effective doping of ns 2 metal ions can enhance the luminescence performance, achieving broadband emission with large Stokes shift and high PLQY. − Furthermore, Sb 3+ as a metal cation with 5s 2 lone pair electrons has better stereo activity and structural tunability of lone pair electrons than that with 6s 2 lone pair electrons and has been widely used as an effective dopant to improve the PL performance. , In 2020, our group introduced Sb 3+ ions in Cs 2 NaInCl 6 to achieve efficient blue luminescence, with PL QY as high as ∼70%. This enhancement is attributed to the fact that Sb 3+ doping breaks the inherent parity-forbidden transition and effectively regulates the density of the state (DOS) population …”

Supramolecular-Interactions-Modulated Photoluminescence in Indium Bromide-Based Isomers

“…The In–Br bond lengths of 1 are in the range of 2.5818(9)–2.7048(9) Å, while those of 2 are in the range of 2.5937(5)–2.6734(5) Å. These In–Br bond distances are slightly shorter than those of the previous report. ,, The distances of In–N are 2.301(6) and 2.311(6) Å in 1 and 2.303(3) and 2.316(3) Å in 2 , which are slightly shorter than those of [In 2 (phen) 3 Cl 6 ]·CH 3 CN . It is notable that the density of 2 is slightly greater than that of 1 .…”

Transient Photoinduced Pb2+ Disproportionation for Exciton Self-Trapping and Broadband Emission in Low-Dimensional Lead Halide Perovskites

“…The broadband emission in these WLE perovskites has been commonly attributed to intrinsic self-trapped excitons (STEs), − ,− distinguishing them from conventional extrinsic defect emission dependent on sample doping and quality. , STEs, quasi-particles composed of localized excitons with deformed lattices, have been proposed in various materials, including condensed rare gases, organic molecule crystals, oxides, chalcogenides, and metal halides. − In low-dimensional perovskites, excitons are formed by the binding of electrons and holes by quantum and dielectric confinement effects. Meanwhile, both long- and short-range exciton–phonon coupling is enhanced due to the soft and polar lattice and reduced dimensionality, facilitating STE formation. , Despite considerable reports of broadband emission in low-dimensional perovskites, the exact electronic and structural nature of these STE species remains elusive, hindering the rational design of high-efficiency WLE materials. − …”