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Abstract We incorporate Se into the 3D halide perovskite framework using the zwitterionic ligand: SeCYS (+NH3(CH2)2Se−), which occupies both the X−and A+sites in the prototypical ABX3perovskite. The new organoselenide‐halide perovskites: (SeCYS)PbX2(X=Cl, Br) expand upon the recently discovered organosulfide‐halide perovskites. Single‐crystal X‐ray diffraction and pair distribution function analysis reveal the average structures of the organoselenide‐halide perovskites, whereas the local lead coordination environments and their distributions were probed through solid‐state77Se and207Pb NMR, complemented by theoretical simulations. Density functional theory calculations illustrate that the band structures of (SeCYS)PbX2largely resemble those of their S analogs, with similar band dispersion patterns, yet with a considerable band gap decrease. Optical absorbance measurements indeed show band gaps of 2.07 and 1.86 eV for (SeCYS)PbX2with X=Cl and Br, respectively. We further demonstrate routes to alloying the halides (Cl, Br) and chalcogenides (S, Se) continuously tuning the band gap from 1.86 to 2.31 eV–straddling the ideal range for tandem solar cells or visible‐light photocatalysis. The comprehensive description of the average and local structures, and how they can fine‐tune the band gap and potential trap states, respectively, establishes the foundation for understanding this new perovskite family, which combines solid‐state and organo‐main‐group chemistry.
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This content will become publicly available on April 1, 2026
Electron-density analysis of halide...halide through-space magnetic exchange
We present a combined experimental and density functional theory study that characterizes the charge and spin density in NiX2(3,5-lutidine)4(X= Cl, Br and I). In this material, magnetic exchange interactions occur via Ni2+–halide...halide–Ni2+pathways, forming one-dimensional chains. We find evidence for weak halide...halide covalency in the iodine system, which is greatly reduced whenX= Br and is absent forX= Cl; this is consistent with the reported `switching-on' of magnetic exchange in the larger-halide cases. Our results are benchmarked against density functional theory calculations on [NiHF2(pyrazine)2]SbF6, in which the primary magnetic exchange is mediated by F–H–F bridging ligands. This comparison indicates that, despite the largely depleted charge density found at the centre of halide...halide bonds, these through-space interactions can support strong magnetic exchange gated by weak covalency and enhanced by significant electron density overlapping that of the transition metal centres.
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- Award ID(s):
- 2104167
- PAR ID:
- 10595624
- Publisher / Repository:
- Journal of Applied Crystallography
- Date Published:
- Journal Name:
- Journal of Applied Crystallography
- Volume:
- 58
- Issue:
- 2
- ISSN:
- 1600-5767
- Page Range / eLocation ID:
- 363 to 373
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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