Photoanode optimization is a fascinating technique for enlightening the power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs). In this present study, V2O5/ ZnO and reduced graphene oxide (rGO)-V2O5/ZnO nanocomposites (NCs) were prepared by the solid-state technique and used as photoanodes for DSSCs. A wet chemical technique was implemented to generate individual V2O5 and ZnO nanoparticles (NPs). The structural characteristics of the as-synthesized NCs were investigated and confirmed using powder X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), and Scanning electron microscope (SEM) with energy dispersive X-ray (EDX) analysis. The average crystallite size (D) of the as-synthesized V2O5/ ZnO and rGO-V2O5/ZnO NCs was determined by Debye-Scherer’s formula. The bandgap (eV) energy was calculated from Tauc’s plots, and the bonding nature and detection of the excitation of electrons were investigated using the Ultra violet (UV) visible spectra, Fourier Transform infrared (FTIR) and photoluminescence (PL) spectral analysis. Electrical studies like Hall effect analysis and the Nyquist plots are also described. The V2O5/ ZnO and rGO-V2O5/ZnO NCs based DSSCs exhibited 0.64% and 1.27% of PCE and the short circuit current densities and open circuit voltages improved from 7.10 to 11.28 mA/cm2 and from 0.57 to 0.68 V, respectively.

Structural, optical and photovoltaic properties of V2O5ZnO and reduced graphene oxide (rGO)-V2O5ZnO nanocomposite photoanodes for dye-sensitized solar cells
    Abstract
    1 Introduction
    2 Experimental details
        2.1 Materials
        2.2 Characterization techniques
        2.3 Synthesis of V2O5 and ZnO nanoparticles
        2.4 Synthesis of rGO-V2O5ZnO nanocomposites
        2.5 Fabrication of photoanodes
        2.6 Fabrication of DSSCs
    3 Results and discussions
        3.1 XRD diffraction analysis
        3.2 SEM with EDX analysis
        3.3 XPS spectrum
        3.4 UV ViS analysis
        3.5 FT-IR spectrum
        3.6 Photoluminescence (PL) spectrum
        3.7 Electrical studies
            3.7.1 Hall effect analyses
            3.7.2 Nyquist plots
        3.8 Photoelectrochemical (PEC) parameters
    4 Conclusions
    Acknowledgements 
    References

• C. Bhagya Lakshmi(Department of Physics, Energy Research Centre, St. Xavier’s College (Autonomous) affiliated to Manonmanium Sundaranar University, Palayamkottai, Tirunelveli 627002, India)
• S. Anna Venus(Department of Physics, Energy Research Centre, St. Xavier’s College (Autonomous) affiliated to Manonmanium Sundaranar University, Palayamkottai, Tirunelveli 627002, India)
• S. Velanganni(Department of Chemistry, Parvathy’s Arts and Science College (affiliated to Madurai Kamaraj University), Dindigul 624002, India)
• A. Muthukrishnaraj(Department of Chemistry, Faculty of Engineering, Karpagam Academy of Higher Education, Coimbatore, Tamil Nadu 641021, India)
• Manikandan Ayyar(Department of Chemistry, Karpagam Academy of Higher Education, Coimbatore, Tamil Nadu 641021, India, Centre for Material Chemistry, Karpagam Academy of Higher Education, Coimbatore, Tamil Nadu 641021, India, Department of Chemistry, Bharath Institute of Higher Education and Research (BIHER), Chennai 600073, Tamil Nadu, India) Corresponding author
• Mohamed Henini(UNESCO UNISA Africa Chair in Nanosciences and Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria, South Africa, Nanosciences African Network (NANO‑AFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West, PO Box: 722, Cape Town 7129, South Africa, School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK)