Polyaniline (PANI)-based hybrid materials have emerged as promising candidates for electronic, optoelectronic and energy storage applications; however, systematic control of their optical band structure and AC electrical transport through dopant engineering remains insufficiently explored. In particular, the combined influence of controlled single (Zn or Ce) and co-doping (Zn–Ce) on the structure–property relationship in PANI matrices has not been clearly established. In this study, polyaniline (PANI)-based Zn, Ce, and Zn–Ce co-doped nanocomposites were synthesized with varying weight percentages (0.5%, 1.5%, and 2.5%) of ZC (Zn–Ce) nanocomposite incorporated into the PANI matrix. The prepared samples, designated as PAZn, PACe, PAZC-1 (0.5 wt%), PAZC-2 (1.5 wt%), and PAZC-3 (2.5 wt%) were synthesized through a controlled chemical oxidative polymerization method to investigate the influence of single and mixed Zn–Ce doping on their, structural, optical and electrical behavior. X-ray diffraction patterns revealed that Zn and Ce single-doped samples exhibited distinct crystalline peaks, while the Zn–Ce co-doped systems showed an amorphous nature in the PANI matrix, and Fourier transform infrared spectroscopy revealed strong interactions between the PANI backbone and Zn/Ce species, indicating effective incorporation and coordination. UV–visible analysis revealed that the indirect optical bandgap (Eind) increases from 1.81 ± 0.02 eV (PAZn) and 1.90 ± 0.02 eV (PACe) to a maximum of 4.49 ± 0.02 eV for PAZC-2, followed by a decrease to 2.97 ± 0.02 eV for PAZC-3. Correspondingly, the Urbach energy, determined from the linear region of ln(α) versus photon energy (hν) plots, varies from 0.66 ± 0.02 eV (PAZn) and 0.86 ± 0.02 eV (PACe) to lower values of 0.23 ± 0.02 eV (PAZC-1) and 0.22 ± 0.02 eV (PAZC-2), before increasing to 0.51 ± 0.02 eV for PAZC-3, indicating composition-dependent modification of localized states and structural disorder. AC conductivity measurements further demonstrate an inverse correlation with bandgap, with the co-doped sample exhibiting reduced conductivity for PAZC-2 (~ 46 S cm⁻1 at 1 MHz) compared to the more disordered compositions for PAZC-3 (~ 136 S cm⁻1 at 1 MHz), reflecting weakened defect-assisted hopping transport. Among the prepared compositions, the electrical and dielectric properties followed the trend PAZC-3 > PAZC-1 > PAZC-2, indicating enhanced interfacial polarization and charge transport with increasing ZC content. This indicates that by using Zn–Ce co-doping in a PANI matrix, both the bandgap widening and AC conductivity inhibiting properties of the materials via improved structural ordering can be realized, highlighting the possible potential of such nanocomposites in optoelectronic and energy storage applications.

Influence of single and co-doping of Zn–Ce on the optical and electrical properties of Polyaniline composites

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发表日期：

2026年4月19日

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K. M. Sandeep,
J. S. Ashwajeet,
M. N. Raghavendra

摘要

Polyaniline (PANI)-based hybrid materials have emerged as promising candidates for electronic, optoelectronic and energy storage applications; however, systematic control of their optical band structure and AC electrical transport through dopant engineering remains insufficiently explored. In particular, the combined influence of controlled single (Zn or Ce) and co-doping (Zn–Ce) on the structure–property relationship in PANI matrices has not been clearly established. In this study, polyaniline (PANI)-based Zn, Ce, and Zn–Ce co-doped nanocomposites were synthesized with varying weight percentages (0.5%, 1.5%, and 2.5%) of ZC (Zn–Ce) nanocomposite incorporated into the PANI matrix. The prepared samples, designated as PAZn, PACe, PAZC-1 (0.5 wt%), PAZC-2 (1.5 wt%), and PAZC-3 (2.5 wt%) were synthesized through a controlled chemical oxidative polymerization method to investigate the influence of single and mixed Zn–Ce doping on their, structural, optical and electrical behavior. X-ray diffraction patterns revealed that Zn and Ce single-doped samples exhibited distinct crystalline peaks, while the Zn–Ce co-doped systems showed an amorphous nature in the PANI matrix, and Fourier transform infrared spectroscopy revealed strong interactions between the PANI backbone and Zn/Ce species, indicating effective incorporation and coordination. UV–visible analysis revealed that the indirect optical bandgap (E_ind) increases from 1.81 ± 0.02 eV (PAZn) and 1.90 ± 0.02 eV (PACe) to a maximum of 4.49 ± 0.02 eV for PAZC-2, followed by a decrease to 2.97 ± 0.02 eV for PAZC-3. Correspondingly, the Urbach energy, determined from the linear region of ln(α) versus photon energy (hν) plots, varies from 0.66 ± 0.02 eV (PAZn) and 0.86 ± 0.02 eV (PACe) to lower values of 0.23 ± 0.02 eV (PAZC-1) and 0.22 ± 0.02 eV (PAZC-2), before increasing to 0.51 ± 0.02 eV for PAZC-3, indicating composition-dependent modification of localized states and structural disorder. AC conductivity measurements further demonstrate an inverse correlation with bandgap, with the co-doped sample exhibiting reduced conductivity for PAZC-2 (~ 46 S cm^⁻1 at 1 MHz) compared to the more disordered compositions for PAZC-3 (~ 136 S cm^⁻1 at 1 MHz), reflecting weakened defect-assisted hopping transport. Among the prepared compositions, the electrical and dielectric properties followed the trend PAZC-3 > PAZC-1 > PAZC-2, indicating enhanced interfacial polarization and charge transport with increasing ZC content. This indicates that by using Zn–Ce co-doping in a PANI matrix, both the bandgap widening and AC conductivity inhibiting properties of the materials via improved structural ordering can be realized, highlighting the possible potential of such nanocomposites in optoelectronic and energy storage applications.