Mn-doped Bi _{2- <i>x</i>} Mn _<i>x</i> O ₃ thin films: structural, optical, and dielectric properties for optoelectronic applications

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 ( ε 1 , ε 2 , Tan δ ) 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.