Comparison of Electrode Structures and Photovoltaic Properties of Porphyrin-Sensitized Solar Cells with TiO₂ and Nb, Ge, Zr-Added TiO₂ Composite Electrodes

Abstract

Electrode structures and photovoltaic properties of porphyrin-sensitized solar cells with TiO2 and Nb-, Ge-, and Zr-added TiO2 composite electrodes were examined to disclose the effects of partial substitution of Ti atom by the other metals in the composite electrodes. The TiO2 and Nb-, Ge-, and Zr-added TiO2 composite electrodes were prepared by sol-gel process using laurylamine hydrochloride as a template for the formation of micellar precursors yielding well-defined mesoporous nanocrystalline structures, as in the cases of the formation of silica and titania tubules and nanoparticles by the templating mechanism. The TiO2 and Nb-, Ge-, and Zr-added TiO2 composite electrodes were characterized by transmission electron microscopy, BET surface area analysis, X-ray diffraction analysis, Raman spectroscopy, and impedance measurements. The TiO2 anatase nanocrystalline structure is retained after doping a small amount (5 mol %) of Nb, Ge, or Zr into the TiO2 structure, suggesting the homogeneous distribution of the doped metals with replacing Ti atom by the doped metal. The power conversion efficiency of the porphyrin-sensitized solar cells increases in the order Zr-added TiO2 (0.8%) < Nb-added TiO2 (1.2%) < TiO2 (2.0%) < Ge-added TiO2 cells (2.4%) under the same conditions. The improvement of cell performance of the Ge-added TiO2 cell results from the negative shift of the conduction band of the Ge-added TiO2 electrode. The Ge-added TiO2 cell exhibited a maximum power conversion efficiency of 3.5% when the porphyrin was adsorbed onto the surface of the Ge-added TiO2 electrode with a thickness of 4 microm in MeOH for 1 h.

Bisquinoxaline‐Fused Porphyrins for Dye‐Sensitized Solar Cells

“…[15][16][17][18][19][20][21] Nevertheless, until recently, the cell performances of porphyrin DSSCs were much lower than those of ruthenium DSSCs as a result of the poor light-harvesting property of typical porphyrins at 450-550 nm and > 600 nm. To overcome this drawback, the perturbation of the porphyrin p system is an effective methodology to tailor the optical, photophysical, and electrochemical properties.…”

“…2,4,6-Trimethylphenyl groups were introduced to increase solubility and to reduce aggregation on TiO 2 . [21] Results and Discussion…”

Metal‐Free Porphyrin‐Sensitized Mesoporous Titania Films For Visible‐Light Indoor Air Oxidation

“…Furthermore, because it is possible to control the photochemical and electrochemical properties by modification of the substituents and selection of the central metal, the porphyrin molecule can expand its role in biological, chemical, and physical research. [1,2] In addition, porphyrin derivatives have found applications for the construction of solar cells as light absorbers in organic dyes displaying notable stability and unique chemical, physical, and spectroscopic properties. [3,4] Nanocrystalline anatase TiO 2 has proven to be an excellent candidate for the use as a low cost photocatalyst as well as for various applications in solar energy conversion.…”

“…After that, the sample was irradiated for 120 min under otherwise identical conditions. The size of the film plates placed into the photocatalytic reactor was 15 cm 2 . All efficiencies of the analyzed samples were calculated after 120 min testing time to ensure steady-state behavior and to avoid adsorption/desorption effects typically occurring at the beginning of the measurement.…”

Improvement of Solar Energy Conversion with Nb‐Incorporated TiO2 Hierarchical Microspheres

“…[41] However, as mentioned above, increasing the Nb concentration leads to a greater TiO 2 rutileto-anatase phase transition, with 47.6 % anatase for the Nb:TiO 2 -20 sample. The band gap of anatase, 3.2 eV, is higher than that of rutile, 3.0 eV, thus leading to a blueshift in the band gap of the Nb:TiO 2 -20 sample.…”