Browsing by Author "Ajani A S"

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    Fabrication and Characterization of Co and Li Doped TiO2 Photoanodes for High Efficiency Dye-Sensitized Solar Cells
    (2024-12) Oladosu, O A; Ogundeji T S; Adegboyega O; Ajani A S; Egbeyale G B; Lana G M; Awodele M K; Adedokun O
    The urgent need for a sustainable energy future has driven global efforts to transition from fossil fuels to renewable energy sources. However, challenges such as escalating energy demands, environmental degradation, and the accelerating climate crisis hinder this transition. Dye-sensitized solar cells (DSSCs) emerge as a promising alternative, offering potential advantages like affordability, flexibility, and enhanced efficiency. Titanium (IV) Oxide (TiO2), a widely studied semiconductor material, has been extensively explored for DSSC applications. However, its inherent limitations, including a wide bandgap, significant charge recombination losses, and low electrical conductivity, impede the development of efficient and cost-effective DSSCs. This study aims to address these challenges and contribute to the advancement of DSSC technology as a viable and sustainable energy solution. DSSCs were fabricated using TiO2 photoanodes doped with cobalt (Co) and lithium (Li) via a one-pot sol-gel synthesis approach. Ruthenium-based dye N719 was utilized as the sensitizer. Characterization techniques, including XRD, FTIR, DRS, FESEM, and EDX, were employed to analyze the structural, optical, morphological, and elemental properties of the synthesized materials. Doping with Co and Li effectively reduced the TiO2 bandgap from 3.18 eV to 3.12 eV and 2.88 eV, respectively, leading to enhanced short-circuit current density (Jsc) values of 10.97 mA/cm² and 12.37 mA/cm², respectively. Among the fabricated DSSCs, the Li-doped TiO2 photoanode demonstrated the highest power conversion efficiency of 5.3%, followed by Co-doped TiO2 (4.2%) and undoped TiO2 (3.3%). These findings highlight the potential of Li and Co-doped TiO2 as promising materials for the development of high-performance DSSCs.
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    Green synthesis and characterization of Graphene/SnO₂ nanocomposite photoanodes for enhanced DSSC performance
    (Nano Plus: Sci. Tech., 2025) Ojo A O; Adedokun K A; Gbadero D S; Oyetunji E O; Adegboyega O; Egbeyale G B; Ajani A S; Awodele M K; Adedokun O
    Dye-sensitized solar cells (DSSCs) offer a compelling alternative to conventional silicon-based solar cells due to their cost-effectiveness, flexibility, and relatively high efficiency. However, their performance is currently hindered by the photoanode material, typically titanium dioxide (TiO₂). This study aims to develop a green synthesis method for graphene/tin dioxide nanocomposites (G/ SnO₂ NCs) using Bryophyllum pinnatum extract for DSSC applications. SnO₂ nanoparticles (SnO2 NPs) were synthesized using a green method with Bryophyllum pinnatum extract and integrated with biomass-derived graphene to fabricate G/SnO₂ NCs for DSSC applications. Characterization techniques, including UV-Vis spectroscopy, XRD, FTIR, SEM, and EDX, were employed to analyze the optical, structural, functional, morphological, and elemental compositional properties of graphene, SnO₂, and the G/SnO₂ NCs. The photoanode thin films were deposited using the doctor blade technique, and their electrical properties were evaluated using four-point probe measurements. Results demonstrate that the G/SnO₂ NCs exhibit significantly enhanced electrical conductivity (0.148 S/m) compared to pristine SnO₂ (0.098 S/m) and graphene (0.122 S/m), indicating improved charge transport properties within the composite material. This enhancement is attributed to the synergistic effect of the high electron mobility of SnO₂ and the excellent conductivity of graphene. Furthermore, the G/SnO₂ NCs exhibit lower sheet resistance (549.48 Ω), further suggesting its potential for efficient charge collection in DSSC applications. The graphene/SnO₂ nanocomposites exhibited enhanced electrical conductivity, improved charge transport properties, and lower sheet resistance compared to pristine SnO₂ and graphene. These findings suggest that the synergistic combination of SnO₂ and graphene offers a promising pathway to improved efficiency in DSSC applications. This research contributes to the development of sustainable and cost-effective solar energy solutions, offering a promising alternative to conventional silicon-based solar cells.