Solubility Limit and Optoelectronic Evolution of Heterovalent Bi3+ Doping in MAPbBr3 Perovskite Powders: A Study from Electrochemical Impedance Spectroscopy (EIS)
4 affiliations
- 1Institut de Fabricació i Producció Automatitzada, Universitat Politècnica de València, Camí de Vera s/n, 46022 València, Spain
- 2Departament de Física, Universitat Jaume I, Avinguda Sos Baynat s/n, 12071 Castellón, Spain
- 3Département des Sciences et Technologie, École Normale Supérieure (ENS) d’Abidjan, Abidjan 08 BP 10, Côte d’Ivoire
- 4Departamento de Termodinámica Aplicada (ETSII), Universitat Politècnica de València, Camí de Vera s/n, 46022 València, Spain
Abstract
This paper reports a comprehensive physicochemical and electrical investigation of MAPb1−xBixBr3 perovskite powders (nominal x = 0 to 0.16) synthesized by antisolvent (acetone) precipitation. Structural (XRD/Rietveld) and chemical (EDX/EDS) analyses reveal a dual-regime doping mechanism governed by a thermodynamic solubility limit, with the true bismuth content saturating at approximately 1.3–1.4 at.% (nominal x ≈ 0.04). Below this limit, bismuth insertion causes anomalous lattice expansion through the creation of lead vacancies (V″Pb) and leads to a marked increase in the absolute intensity of the main diffraction peak, despite a slight broadening of the FWHM driven by local lattice microstrains. Above the limit, excess bismuth is expelled toward the grain boundaries as a highly disordered, amorphous-like, or short-range segregated secondary phase, degrading crystallinity and narrowing the effective optical band gap by up to 35 meV (from 2.278 eV to 2.243 eV) following an initial stabilization at low introduction levels (1–2% Bi), driven by the tentative formation of localized sub-gap defect states (Urbach-type tails) rather than intrinsic band-structure reorganization. Electrochemical impedance spectroscopy (EIS) confirms this dual regime: the absence of an electrode-polarization peak in ε″ indicates a Maxwell–Wagner–Sillars-type response, allowing the bulk conductivity to be extracted directly from the dielectric loss. At low temperatures, two distinct conduction regions coexist—a high-frequency electronic (hole-like) process and a low-frequency ionic process linked to bismuth-related defects, with ionic transport becoming dominant at high temperature; correspondingly, the dc-conductivity activation energy decreases from 66.3 kJ/mol (x = 0) to 30.7 kJ/mol (x = 0.16). Finally, the high-frequency limiting permittivity and geometric capacitance increase significantly with bismuth content (from ~15 pF to ~30 pF), reflecting enhanced dielectric performance driven by defect engineering.
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BibTeX
@article{dao2026solubility,
title = {{Solubility Limit and Optoelectronic Evolution of Heterovalent Bi3+ Doping in MAPbBr3 Perovskite Powders: A Study from Electrochemical Impedance Spectroscopy (EIS)}},
author = {Péyèna Yacouba Dao and Andreu Andrio and Júlia Marí-Guaita and Giulia Longo and Shafi Ullah and Donafologo Soro and Álvaro Montero Reguera and Bernabé Mari Soucase and Vicente Compañ},
journal = {Nanomaterials},
year = {2026},
month = oct,
doi = {10.3390/nano16201319},
url = {https://www.mdpi.com/2079-4991/16/20/1319},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Solubility Limit and Optoelectronic Evolution of Heterovalent Bi3+ Doping in MAPbBr3 Perovskite Powders: A Study from Electrochemical Impedance Spectroscopy (EIS)
AU - Péyèna Yacouba Dao
AU - Andreu Andrio
AU - Júlia Marí-Guaita
AU - Giulia Longo
AU - Shafi Ullah
AU - Donafologo Soro
AU - Álvaro Montero Reguera
AU - Bernabé Mari Soucase
AU - Vicente Compañ
PY - 2026
DA - 2026/10/01
JO - Nanomaterials
DO - 10.3390/nano16201319
UR - https://www.mdpi.com/2079-4991/16/20/1319
AB - This paper reports a comprehensive physicochemical and electrical investigation of MAPb1−xBixBr3 perovskite powders (nominal x = 0 to 0.16) synthesized by antisolvent (acetone) precipitation. Structural (XRD/Rietveld) and chemical (EDX/EDS) analyses reveal a dual-regime doping mechanism governed by a thermodynamic solubility limit, with the true bismuth content saturating at approximately 1.3–1.4 at.% (nominal x ≈ 0.04). Below this limit, bismuth insertion causes anomalous lattice expansion through the creation of lead vacancies (V″Pb) and leads to a marked increase in the absolute intensity of the main diffraction peak, despite a slight broadening of the FWHM driven by local lattice microstrains. Above the limit, excess bismuth is expelled toward the grain boundaries as a highly disordered, amorphous-like, or short-range segregated secondary phase, degrading crystallinity and narrowing the effective optical band gap by up to 35 meV (from 2.278 eV to 2.243 eV) following an initial stabilization at low introduction levels (1–2% Bi), driven by the tentative formation of localized sub-gap defect states (Urbach-type tails) rather than intrinsic band-structure reorganization. Electrochemical impedance spectroscopy (EIS) confirms this dual regime: the absence of an electrode-polarization peak in ε″ indicates a Maxwell–Wagner–Sillars-type response, allowing the bulk conductivity to be extracted directly from the dielectric loss. At low temperatures, two distinct conduction regions coexist—a high-frequency electronic (hole-like) process and a low-frequency ionic process linked to bismuth-related defects, with ionic transport becoming dominant at high temperature; correspondingly, the dc-conductivity activation energy decreases from 66.3 kJ/mol (x = 0) to 30.7 kJ/mol (x = 0.16). Finally, the high-frequency limiting permittivity and geometric capacitance increase significantly with bismuth content (from ~15 pF to ~30 pF), reflecting enhanced dielectric performance driven by defect engineering.
SN - 2079-4991
ER -