This study investigates the fabrication and characterization of microwaves assisted Bismuth-doped graphitic carbon nitride (Bi@g-C3N4)composite into TiO2 as a photoanode material, for dye-sensitized solar cells (DSSC). The effect of Bi@g-C3N4/TiO2 was evaluated through photovoltaic performance measurements, revealing significant increases in power conversion efficiency (PCE) from 2.70% for Pure TiO2 to 9.22% for Bi@g-C3N4/TiO2, which are sensitized with anthocyanin at acidic medium. This improvement areattributed to improved light harvesting and reduced charge recombination. Additionally, the fill factor was improved from 0.46 to 0.50, respectively. The structural and compositional properties of Bi@g-C3N4/TiO2 were characterized using FTIR, XRD, SEM, EDX, and DRS. For a better understanding of the practical work, theoretical studies were performed for Bi@g-C₃N₄ as a photoanode for DSSCs. Density functional theory (DFT) calculations demonstrate that bismuth doping reduces the band gap, which introduces extra states, hence, enhances the density of states near the Fermi level, leading to more visible-light absorption and charge carrier density. As for optical properties, specifically dielectric function and conductivity spectra show better polarization effect and electron mobility. The molecular orbital study of Anthocyanin&Bi@g-C₃N₄ also shows more energy level order, which facilitates electron injection and charge separation. SEM and EDX results show the good dispersion of porous nanoparticles with homogeneous composition, where 7.36% Bi by weight is present, indicating successful doping and composite formation. The efficiency is also improved in acidic medium (pH1), showing improved charge separation and reduced recombination, while at higher pH values, lower efficiencies are observed (1.04% at pH 7 and 0.54% at pH 12). Furthermore, DFT and TD-DFT calculations show that Bi doping facilitates electron injection, recombination barriers are reduced, and absorption peaks are also shifted from 456 nm to 491 nm, which improve light harvesting and efficiency. Finally, the synergistic increase in light harvesting, charge generation, and transport makes Bi@g-C₃N₄ a good candidate for high-efficiency photovoltaic applications.
عرض المزيد
عرض أقل