Bonding topology and electronic characterization of mechanochemically synthesized CsCuBr3 as a lead-free p-type semiconductor
4 affiliations
- 1Facultad de Química y de Farmacia, Pontificia Universidad Católica de Chile Santiago Chile
- 2Departamento de Química, Universidad Católica Del Norte Antofagasta Chile
- 3Departamento de Química Analítica e Inorgánica, Facultad de Ciencias Químicas, Universidad de Concepción Concepción Chile
- 4Instituto de Ciencias Aplicadas, Facultad de Ingeniería, Universidad Autónoma de Chile Santiago Chile
Abstract
In this work, we present a systematic study of the copper halide compound CsCuBr3, combining mechanochemical synthesis with structural, spectroscopic, electrochemical, and first-principles investigations. Phase-pure orthorhombic CsCuBr3 (space group C2221) was obtained after 3 h of planetary ball milling under atmospheric conditions. Structural and microstructural evolution were carefully monitored via Rietveld refinement and Williamson–Hall analysis, while X-ray photoelectron spectroscopy confirmed the expected composition and the Cu2+ oxidation state. Diffuse reflectance spectroscopy revealed broad absorption extending from the UV to the near-infrared, consistent with charge transfer and Cu2+ d–d transitions. The optical band gap determined using the inverse logarithmic derivative method was 1.40 eV ± 0.04 eV, with a transition parameter of m = 0.49 ± 0.01, consistent with a direct-allowed transition. Spin-polarized DFT + U calculations including spin–orbit coupling yielded a narrow direct gap of 1.29 eV and a weakly antiferromagnetic lowest-energy configuration. QTAIM analysis revealed a non-trivial bonding topology within the strongly Jahn–Teller distorted [Cu2Br9]5− unit, showing that only four of the six Cu–Br contacts contain bond critical points, and these do not correspond simply to the four shortest Cu–Br distances. Electrochemical measurements yielded frontier energy levels of EVB = −5.14 eV and ECB = −3.62 eV, while Mott–Schottky analysis was consistent with p-type behavior, with an acceptor density of ∼1016 cm−3 and a flat-band potential of 0.79 V vs. Ag/Ag+. These results establish a detailed relationship between the local bonding topology and electronic structure of CsCuBr3 and highlight its potential for further investigation in lead-free optoelectronic applications.
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BibTeX
@article{saavedra2026bonding,
title = {{Bonding topology and electronic characterization of mechanochemically synthesized CsCuBr3 as a lead-free p-type semiconductor}},
author = {Felipe Saavedra and Pablo Garrido and Alifhers Mestra and Mauricio A. Vega-Pallauta and Karem Gallardo and Rodrigo Castillo},
journal = {RSC advances},
year = {2026},
month = oct,
doi = {10.1039/d6ra08279c},
url = {https://europepmc.org/article/PMC/PMC13671112},
note = {CC BY-NC},
}
RIS
TY - JOUR
TI - Bonding topology and electronic characterization of mechanochemically synthesized CsCuBr3 as a lead-free p-type semiconductor
AU - Felipe Saavedra
AU - Pablo Garrido
AU - Alifhers Mestra
AU - Mauricio A. Vega-Pallauta
AU - Karem Gallardo
AU - Rodrigo Castillo
PY - 2026
DA - 2026/10/15
JO - RSC advances
DO - 10.1039/d6ra08279c
UR - https://europepmc.org/article/PMC/PMC13671112
AB - In this work, we present a systematic study of the copper halide compound CsCuBr3, combining mechanochemical synthesis with structural, spectroscopic, electrochemical, and first-principles investigations. Phase-pure orthorhombic CsCuBr3 (space group C2221) was obtained after 3 h of planetary ball milling under atmospheric conditions. Structural and microstructural evolution were carefully monitored via Rietveld refinement and Williamson–Hall analysis, while X-ray photoelectron spectroscopy confirmed the expected composition and the Cu2+ oxidation state. Diffuse reflectance spectroscopy revealed broad absorption extending from the UV to the near-infrared, consistent with charge transfer and Cu2+ d–d transitions. The optical band gap determined using the inverse logarithmic derivative method was 1.40 eV ± 0.04 eV, with a transition parameter of m = 0.49 ± 0.01, consistent with a direct-allowed transition. Spin-polarized DFT + U calculations including spin–orbit coupling yielded a narrow direct gap of 1.29 eV and a weakly antiferromagnetic lowest-energy configuration. QTAIM analysis revealed a non-trivial bonding topology within the strongly Jahn–Teller distorted [Cu2Br9]5− unit, showing that only four of the six Cu–Br contacts contain bond critical points, and these do not correspond simply to the four shortest Cu–Br distances. Electrochemical measurements yielded frontier energy levels of EVB = −5.14 eV and ECB = −3.62 eV, while Mott–Schottky analysis was consistent with p-type behavior, with an acceptor density of ∼1016 cm−3 and a flat-band potential of 0.79 V vs. Ag/Ag+. These results establish a detailed relationship between the local bonding topology and electronic structure of CsCuBr3 and highlight its potential for further investigation in lead-free optoelectronic applications.
SN - 2046-2069
ER -