TiO ₂ /silver/carbon nanotube nanocomposite working electrodes for high-performance dye-sensitized solar cells

In this study, we developed a new way to increase the efficiency of dye-sensitized solar cells by using TiO ₂ /silver/carbon nanotube composites as the working electrode. Silver nanoparticles and multi-walled carbon nanotubes were mixed with TiO ₂ nanoparticles and used as working electrodes in a dye-sensitized solar cell. The effect of the silver nanoparticles and multi-walled carbon nanotubes on the efficiency of the dye-sensitized solar cell was studied as function of their volume fractions using several microscopic and spectroscopic characterization techniques such as scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, ultra-violet-vis and electrochemical impedance spectroscopy. It was found that the silver nanoparticles could induce surface plasmonic phenomena, where the light absorption was enhanced in the ultra-violet wavelength range. Additionally, the carbon nanotubes could increase the electron mobility in the working electrode due to their high surface-to-volume ratio and superior electrical conductivity. The efficiency of the silver/carbon nanotube/TiO ₂ nanocomposite working electrode was compared with that of a conventional TiO ₂ working electrode under one-sun illumination (100 mWcm ^–2 , AM 1.5 G). The TiO ₂ /Ag/carbon nanotube nanocomposite working electrode had a two-fold higher efficiency (3.76%) than the conventional pure TiO ₂ working electrode (1.88%).