J. Eur. Opt. Society-Rapid Publ. 2026, 22, 2 Ó The Author( s), published by EDP Sciences, 2026 https:// doi. org / 10.1051 / jeos / 2025054 Available online at: https:// jeos. edpsciences. org
Journal of the European Optical Society-Rapid Publications
Nano-optoelectronics: from novel materials and nanostructures to innovative applications RESEARCH ARTICLE
Mn-doped Bi 2-x Mn x O 3 thin films: structural, optical, and dielectric properties for optoelectronic applications
Wael M. Mohammed 1, Fatemah H. Alkallas 2, Amira Ben Gouider Trabelsi 2, Mohamed S. I. Koubisy 3, Ibrahim M. Sharaf 3, and Abdelaziz M. Aboraia 3,*
1 Physics Department, Faculty of Science, Minia University, P. O. Box 61519, Minia, Egypt 2 Department of Physics, College of Science, Princess Nourah Bint Abdulrahman University, P. O. Box 84428, Riyadh 11671,
Saudi Arabia 3 Physics Department, Faculty of Science, Al-Azhar University, Assiut Branch, Assiut 71524, Egypt
Received 12 September 2025 / Accepted 5 December 2025
Abstract. The current research investigates the influence of manganese( Mn) doping on the structural, optical, and dielectric properties of Bi 2-x Mn x O 3 thin films for optoelectronic applications. The prepared thin films with different Mn content( x = 0, 0.025, 0.05, 0.075, and 0.1) were synthesized, and their characteristics were thoroughly analyzed. Our findings demonstrate that increasing manganese content enhances light absorption by creating new electronic states, which is reflected in higher absorbance and lower transmittance values. The direct optical band gap decreases with higher Mn incorporation( from 3.60 eV for x = 0 – 3.29 eV for x = 0.1), suggesting a tunable electronic structure. Furthermore, the Urbach energy increases with Mn concentration from 1.23 eV for x = 0 – 3.33 eV for x = 0.1, indicating enhanced structural disorder and broadening of the band tail, which can benefit photovoltaic applications. Analysis of refractive index, extinction coefficient, and dielectric parameters( e 1, e 2, Tand) demonstrates improved optical density, dielectric polarization, and reduced dielectric losses with Mn doping. These results establish clear correlations between Mn concentration and the resulting physical properties, providing crucial insights for optimizing Bi 2 O 3-based materials for high-performance optoelectronic applications.
Keywords: Optical properties, Absorbance, Bandgap narrowing, Electronic transitions, Refractive index, Photocatalysis.
1 Introduction
Understanding semiconductor materials’ structural, optical, and dielectric properties, especially when they these materials are made into thin films, is crucial because these materials play a key role in today’ s electronic and optoelectronic devices [ 1 – 4 ]. Among various metal oxides, bismuth oxide( Bi 2 O 3) is distinguished by its advantageous characteristics, including a high refractive index, significant dielectric permittivity, a wide optical band gap, and notable photoconductivity [ 5, 6 ]. Thanks to these properties, Bi 2 O 3 thin films show great promise for various uses, including optical coatings, gas sensors, photocatalytic systems, and other optoelectronic components [ 5, 7 ].
However, the intrinsic properties of pure Bi 2 O 3 may not always fulfill the precise requirements for advanced device applications [ 8, 9 ]. Modifying these properties through
* Corresponding author: a. m. aboraia @ gmail. com; a. m. aboraia @ azhar. edu. eg controlled doping with suitable elements presents a wellestablished and effective strategy [ 9 ]. The introduction of dopant ions into the host lattice can significantly alter the crystal structure of the material, defect chemistry, electronic band structure, and, consequently, its optical and electrical behavior [ 10, 11 ]. Manganese( Mn) is a particularly intriguing dopant for Bi 2 O 3, given the differences in ionic radius and valence state between Mn 2 + and Bi 3 + [ 12, 13 ]. Incorporating Mn is anticipated to induce lattice strain, modify defect concentrations( such as oxygen vacancies for charge compensation), and alter the electronic density of states, thereby offering a pathway to tune the material’ s functional properties for optoelectronic applications precisely [ 14, 15 ].
While numerous studies have explored the properties of pure and doped Bi 2 O 3 systems, a comprehensive and systematic investigation into the influence of varying Mn ratios on the correlated structural, optical, and dielectric characteristics of Bi 2-x Mn x O 3 films is highly warranted. Understanding how parameters such as crystallite size,
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