Crystal structure of the rhombohedral vacancy-ordered perovskite (CH₃NH₃)₂[SnCl₆] for deep-UV optoelectronic applications.
5 affiliations
- 1Laboratory of Spectroscopic Characterization and Optical Materials, Faculty of Sciences, University of Sfax B.P. 1171 Sfax 3000 Tunisia [email protected].
- 2Department of Physics, Faculty of Science, Elmergib University Libya.
- 3Department of Physics, Al-Qunfudah University College, Umm Al-Qura University Mecca Saudi Arabia.
- 4Institut des Molécules et Matériaux Du Mans (IMMM), UMR-6283 CNRS, Le Mans Université Avenue Olivier Messiaen F-72085 Le Mans Cedex 9 France [email protected].
- 5Interfaces, Confinement, Matériaux et Nanostructures (ICMN), UMR-7374 CNRS, Université D'Orléans 3 Avenue de la Recherche Scientifique Orléans Cedex 45071 France.
Abstract
Lead-free zero-dimensional (0D) hybrid halide perovskites A₂SnX₆ are promising candidates for stable deep-UV optoelectronics; however, the chloride end-members of the series remain underexplored. This study presents a comprehensive structural, optical, and electrical characterization of the vacancy-ordered hybrid hexachlorostannate, (CH₃NH₃)₂[SnCl₆], synthesized via controlled slow evaporation. Single crystal X-ray diffraction, combined with Raman spectroscopy, shows that this hybrid halide has a trigonal structure (space group R3̄m) composed of isolated [SnCl₆]²⁻ octahedra dynamically coupled to methylammonium cations via a robust N-H⋯Cl hydrogen-bonding network. Optical absorption analysis reveals behaviour characteristic of wide-bandgap semiconductor, dominated by ligand-to-metal charge-transfer (LMCT) transitions. Tauc and Urbach analyses yield a direct optical bandgap of ∼3.54 eV and an Urbach energy of 0.17 eV, highlighting the role of dynamic cation disorder in broadening the absorption edge. Furthermore, temperature-dependent impedance spectroscopy (323-413 K) demonstrates thermally activated small-polaron hopping. The AC conductivity is rigorously described by the Correlated Barrier Hopping (CBH) model (W M = 0.201 eV, E a = 0.30 eV). The frequency exponent decreases monotonically with temperature, confirming that charge transport is governed by coulombically correlated hopping between localized Sn-centered states, heavily modulated by grain boundary resistance and organic sublattice dynamics. These findings establish (CH₃NH₃)₂[SnCl₆] as a structurally robust, lead-free reference material, offering a tunable platform for deep-UV photodetection and wavelength-selective optoelectronic applications.
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BibTeX
@article{ibrahmi2026crystal,
title = {{Crystal structure of the rhombohedral vacancy-ordered perovskite (CH₃NH₃)₂[SnCl₆] for deep-UV optoelectronic applications.}},
author = {Imen Ibrahmi and Saber Nasri and Rima Mohammed Altalib and Wael Z El-Sayad and Sandy Auguste and Jean-François Bardeau and Gwenael Corbel and Abderrazek Oueslati},
journal = {RSC advances},
year = {2026},
month = oct,
doi = {10.1039/d6ra08270j},
url = {https://europepmc.org/article/MED/42891169},
note = {CC BY-NC},
}
RIS
TY - JOUR
TI - Crystal structure of the rhombohedral vacancy-ordered perovskite (CH₃NH₃)₂[SnCl₆] for deep-UV optoelectronic applications.
AU - Imen Ibrahmi
AU - Saber Nasri
AU - Rima Mohammed Altalib
AU - Wael Z El-Sayad
AU - Sandy Auguste
AU - Jean-François Bardeau
AU - Gwenael Corbel
AU - Abderrazek Oueslati
PY - 2026
DA - 2026/10/16
JO - RSC advances
DO - 10.1039/d6ra08270j
UR - https://europepmc.org/article/MED/42891169
AB - Lead-free zero-dimensional (0D) hybrid halide perovskites A₂SnX₆ are promising candidates for stable deep-UV optoelectronics; however, the chloride end-members of the series remain underexplored. This study presents a comprehensive structural, optical, and electrical characterization of the vacancy-ordered hybrid hexachlorostannate, (CH₃NH₃)₂[SnCl₆], synthesized via controlled slow evaporation. Single crystal X-ray diffraction, combined with Raman spectroscopy, shows that this hybrid halide has a trigonal structure (space group R3̄m) composed of isolated [SnCl₆]²⁻ octahedra dynamically coupled to methylammonium cations via a robust N-H⋯Cl hydrogen-bonding network. Optical absorption analysis reveals behaviour characteristic of wide-bandgap semiconductor, dominated by ligand-to-metal charge-transfer (LMCT) transitions. Tauc and Urbach analyses yield a direct optical bandgap of ∼3.54 eV and an Urbach energy of 0.17 eV, highlighting the role of dynamic cation disorder in broadening the absorption edge. Furthermore, temperature-dependent impedance spectroscopy (323-413 K) demonstrates thermally activated small-polaron hopping. The AC conductivity is rigorously described by the Correlated Barrier Hopping (CBH) model (W M = 0.201 eV, E a = 0.30 eV). The frequency exponent decreases monotonically with temperature, confirming that charge transport is governed by coulombically correlated hopping between localized Sn-centered states, heavily modulated by grain boundary resistance and organic sublattice dynamics. These findings establish (CH₃NH₃)₂[SnCl₆] as a structurally robust, lead-free reference material, offering a tunable platform for deep-UV photodetection and wavelength-selective optoelectronic applications.
SN - 2046-2069
ER -