In this study, biopolymer composites based on chitosan (CS) with enhanced optical properties were functionalized using Manganese metal complexes and black tea solution dyes. The results indicate that CS with Mn2+-complexes can produce polymer hybrids with high absorption, high refractive index and controlled optical band gaps, with a significant reduction from 6.24 eV to 1.21 eV. The refractive index and optical dielectric constant measurements show that the doped CS films have more charge carriers and traps than those in pure CS films. The Lorentz-Drude model was used to derive several significant optical parameters, and the W-D model was utilized to calculate the optical moments M-1 changing from 0.35 to 2.13 and M-3 changing from 0.005 to 0.4. It was shown that the doped samples have larger Urbach energy than pure film, increased from 0.29 to 0.55 eV. Tauc and ASF model was also used to calculate the electronic transitions, band structure, and optical characteristics. Bandgap energy based on Tauc model at m = 2, 1/3, 1/2, and 2/3 are 1.77, 1.54, 1.47, and 1.37 eV, based on ASF model are 1.52, 1.42, 1.69, and 1.47 eV, respectively. As a result of changes in the optical diffraction parameters the optical mobility (<InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41598_2025_87353_Article_IEq1.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="30" /> </InlineMediaObject> <EquationSource Format="TEX">\({\mu }_{opt}\)</EquationSource> </InlineEquation>) changed from 1.67 to 1.27 and optical resistivity <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41598_2025_87353_Article_IEq2.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="29" /> </InlineMediaObject> <EquationSource Format="TEX">\({\rho }_{opt}\)</EquationSource> </InlineEquation> from 9.36 × 10–27 to 4.0 × 10–29. The dopped samples show an increase in their linear optical susceptibility, third-order nonlinear optical susceptibility and nonlinear refractive indices, changing from 3.165 × 10–15 to 2.831 × 10–12 esu. Finally, light propagation velocities, surface resistance, and thermal emissivity were also examined.

Optical band gap modulation in functionalized chitosan biopolymer hybrids using absorption and derivative spectrum fitting methods: A spectroscopic analysis

期刊论文
出版模式：

开放获取
发表日期：

2025年1月25日

查看全文

Dyari M. Mamand,
Dana S. Muhammad,
Daron Q. Muheddin,
Karzan A. Abdalkarim,
Dana A. Tahir,
Hawkar A. Muhammad,
Shujahadeen B. Aziz,
Sarkawt A. Hussen,
Jamal Hassan

摘要

In this study, biopolymer composites based on chitosan (CS) with enhanced optical properties were functionalized using Manganese metal complexes and black tea solution dyes. The results indicate that CS with Mn²⁺-complexes can produce polymer hybrids with high absorption, high refractive index and controlled optical band gaps, with a significant reduction from 6.24 eV to 1.21 eV. The refractive index and optical dielectric constant measurements show that the doped CS films have more charge carriers and traps than those in pure CS films. The Lorentz-Drude model was used to derive several significant optical parameters, and the W-D model was utilized to calculate the optical moments M_-1 changing from 0.35 to 2.13 and M_-3 changing from 0.005 to 0.4. It was shown that the doped samples have larger Urbach energy than pure film, increased from 0.29 to 0.55 eV. Tauc and ASF model was also used to calculate the electronic transitions, band structure, and optical characteristics. Bandgap energy based on Tauc model at m = 2, 1/3, 1/2, and 2/3 are 1.77, 1.54, 1.47, and 1.37 eV, based on ASF model are 1.52, 1.42, 1.69, and 1.47 eV, respectively. As a result of changes in the optical diffraction parameters the optical mobility ( \({\mu }_{opt}\) ) changed from 1.67 to 1.27 and optical resistivity \({\rho }_{opt}\) from 9.36 × 10^–27 to 4.0 × 10^–29. The dopped samples show an increase in their linear optical susceptibility, third-order nonlinear optical susceptibility and nonlinear refractive indices, changing from 3.165 × 10^–15 to 2.831 × 10^–12 esu. Finally, light propagation velocities, surface resistance, and thermal emissivity were also examined.