Dye-Sensitized Solar Cells Based on an N-Doped TiO2 and TiO2-Graphene Composite Electrode

• Published in: Journal of electronic materials 2018-10, Vol.47 (10), p.6241-6250
• Main Authors: Mousa, M. A., Khairy, M., Mohamed, H. M.
• Format: Article
• Language: English
• Subjects: Anatase; Characterization and Evaluation of Materials; Chemistry and Materials Science; Dye-sensitized solar cells; Dyes; Electron transport; Electronics and Microelectronics; Energy conversion efficiency; Fluorine; Fourier transforms; Graphene; Infrared analysis; Infrared spectroscopy; Instrumentation; Materials Science; Nitrogen; Optical and Electronic Materials; Optical measurement; Photovoltaic cells; Reduction; Reflectance; Solid State Physics; Spectrum analysis; Surface area; Tin oxides; Titanium dioxide; Ultraviolet reflection; X ray photoelectron spectroscopy; X-ray diffraction
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-018-6530-0

In this work, the effect of graphene and nitrogen doping on the performance of dye-sensitized solar cells of pure TiO 2 was studied. Pure and N-doped TiO 2 nanoparticles were synthesized using a hydrothermal method, while graphene was prepared through the reduction of graphene oxide. The materials were characterized using x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FT-IR), Raman, Brunauer–Emmett–Teller surface area analysis (BET) and ultraviolet-visible (UV-Vis) diffusion reflectance spectroscopy. Nitrogen dopant concentration varied from 0 at.% to 1.57 at.%. The results confirmed that all N-doped samples exhibited pure anatase phase with an average diameter in the range of 7–12 nm. The pore volume and BET surface area increased with the amount of nitrogen in TiO 2 . XPS investigation displayed an N1s peak around 397 eV, which suggested N-Ti-O structure in the TiO 2 matrix. Moreover, optical measurements showed that the optical absorption edge of N-doped TiO 2 exhibited a significant shift from ultraviolet to visible light region in comparison with pure TiO 2 . Dye-sensitized solar cells (DSSCs) were fabricated using N719 dye and various TiO 2 based photoanodes. The photoanode of N-doped TiO 2 modified with graphene showed the highest energy-conversion efficiency of 6.3%, while the efficiencies of pure and N-doped TiO 2 cells are 0.41% and 1.21%, respectively. The improvement in conversion efficiency of graphene-based DSSC was attributed to the formed electron bridges between TiO 2 and fluorine-doped tin oxide (FTO), which led to a reduction in the recombination rate of electron-hole pairs and an increase in the rate of electron transport.