Loading...

Controlling electron transport rate and recombination process of TiO 2 dye-sensitized solar cells by design of double-layer films with different arrangement modes

Bakhshayesh, A. M ; Sharif University of Technology

1561 Viewed
  1. Type of Document: Article
  2. DOI: 10.1016/j.electacta.2012.06.087
  3. Abstract:
  4. TiO 2 dye-sensitized solar cells (DSSCs) in the form of double-layer films, containing an under-layer and an over-layer, with various crystal structures (i.e., anatase and rutile phases) and morphologies (i.e., nanoparticle and nanowire) were reported. It was found that the photovoltaic performance of TiO 2 DSSCs depends on the morphology, crystal structure, light scattering effect, optical band gap energy and arrangement of the under- and over-layer films. The double-layer solar cell made of anatase-TiO 2 nanoparticles as the under-layer and anatase-TiO 2 nanowires as the over-layer (i.e., AW solar cell) showed the highest power conversion efficiency and fill factor of 6.34% and 62.6%, respectively. High electron lifetime, rapid transportation and less recombination of photogenerated electrons are the factors affect the efficiency improvement of AW film and was demonstrated by electrochemical impedance spectroscopy (EIS). X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM) analyses revealed that TiO 2 nanoparticles had uniform and nanometer grains with particle size around 20 nm, whereas TiO 2 nanowires with length of several μm had diameter in the range 20-50 nm. The optical properties and band gap energies of TiO 2 nanoparticles and nanowires were studied through UV-vis absorption. The indirect optical band gap energy of TiO 2 nanowires, anatase-TiO 2 and rutile-TiO 2 nanoparticles was calculated 3.61, 3.47 and 3.41 eV, respectively. The design of double-layer solar cells by manipulation of morphology and crystal structure of TiO 2 nanostructures will open a new concept for improvement of power conversion efficiency of dye sensitized solar cells
  5. Keywords:
  6. Double-layer ; EIS ; TiO 2 nanoparticles ; TiO 2 nanowires ; Band gap energy ; Double layers ; Double-layer films ; Dye-sensitized solar cell ; Dye-sensitized solar cells ; Efficiency improvement ; EIS ; Electron lifetime ; Electron transport rate ; Field emission scanning electron microscopes ; Fill factor ; Manipulation of morphology ; Nanometer grains ; Optical band gap energy ; Photogenerated electrons ; Photovoltaic performance ; Power conversion efficiencies ; Recombination process ; Rutile phasis ; Scattering effects ; TiO ; UV-vis absorptions ; Conversion efficiency ; Electrochemical impedance spectroscopy ; Morphology ; Nanoparticles ; Nanowires ; Optical band gaps ; Optical properties ; Oxide minerals ; Photoelectrochemical cells ; Titanium dioxide ; X ray diffraction ; Solar cells
  7. Source: Electrochimica Acta ; Volume 78 , 2012 , Pages 384-391 ; 00134686 (ISSN)
  8. URL: http://www.sciencedirect.com/science/article/pii/S0013468612010638