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ABSTRACT: Transient mobility spectroscopy (TMS) is presented as a new tool to probe the charge carrier mobility of commonly employed organic and inorganic semiconductors over the relevant range of charge densities. The charge density dependence of the mobility of semiconductors used in hybrid and organic photovoltaics gives new insights into charge transport phenomena in solid state dye sensitized solar cells.
Advanced Materials 05/2013; · 13.88 Impact Factor
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ABSTRACT: A simple selective etching process easily removed a 2nd anodized TiO(2) nanotubes (TNTs) layer from a physically stable 1st anodized TNTs layer to produce noncurling, freestanding, large-area aligned doubly open-ended TNTs. These TNTs were easily transferred to a conducting glass for use in fabricating front-illuminated dye sensitized solar cells.
Chemical Communications 06/2012; 48(70):8748-50. · 6.17 Impact Factor
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ABSTRACT: The interfacial properties were systematically investigated using an organic sensitizer (3-(5'-{4-[(4-tert-butyl-phenyl)-p-tolyl-amino]-phenyl}-[2,2']bithiophenyl-5-yl)-2-cyano-acrylic acid (D)) and inorganic sensitizer (bis(tetrabutylammonium) cis-bis(thiocyanato)bis(2,2'-bipyridine-4,4'-dicarboxylato) ruthenium(II) (N719)) in a liquid-state and a solid-state dye-sensitized solar cell (DSC). For liquid-DSCs, the faster charge recombination for the surface of D-sensitized TiO(2) resulted in shorter diffusion length (L(D)) of ∼3.9 μm than that of N719 (∼7.5 μm), limiting the solar cell performance at thicker films used in liquid-DSCs. On the other hand, for solid-DSCs using thin TiO(2) films (∼ 2 μm), D-sensitized device outperforms the N719-sensitized device in an identical fabrication condition, mainly due to less perfect wetting ability of solid hole conductor into the porous TiO(2) network, inducing the dye monolayer act as an insulation layer, while liquid electrolyte is able to fully wet the surface of TiO(2). Such insulation effect was attributed to the fact that the significant increase in recombination resistance (from 865 to 4,400 Ω/cm(2)) but shorter electron lifetime (from 10.8 to 0.8 ms) when compared to liquid-DSCs. Higher recombination resistance for solid-DSCs induced the electron transport-limited situation, showing poor performance of N719-sensitized device which has shorter electron transport time and similar L(D) (2.9 μm) with D-sensitized device (3.0 μm).
ACS Applied Materials & Interfaces 06/2012; · 4.53 Impact Factor
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Advanced Energy Materials. 01/2012; 2:219-224.
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RSC Advances. 01/2012; 2:3467–3472.
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Journal of Materials Chemistry 01/2012; 22:8641–8648. · 5.97 Impact Factor
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ABSTRACT: TiO(2) electrodes, sensitized with the N719 dye at high immersion temperatures during the sensitization process, were found to have large fractions of weakly bound N719 on the electrode surface, which resulted in dye aggregation and decreased device longevity. These disadvantages were ameliorated using a low-temperature stearic acid (SA)-assisted anchoring method described here. The activation energy (ΔE(NS)(++)) and relative fraction of strongly bound N719 were twice as large as the respective values obtained without the use of SA. Slowing of adsorption, both by thermal means and through SA-mediated processes, effectively controlled the binding mode of N719 on the surface of TiO(2). The resulting sensitized electrodes displayed enhanced device longevity and improved generation of photoinduced electrons.
Langmuir 12/2011; 27(23):14647-53. · 4.19 Impact Factor
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ABSTRACT: A novel bis-EDOT-based monomer with ethylene glycol oligomers was synthesized and shown to exhibit strong ion solvation, good transport properties, and effective charge screening. These properties greatly improved J(SC) (4.2 to 7.0 mA cm(-2)) and η (1.6 to 2.9%) in an iodine-free solid state dye-sensitized solar cell (DSSC) employing a Z-907 sensitizer, compared with the corresponding values of DSSCs fabricated using the standard bis-EDOT.
Chemical Communications 08/2011; 47(37):10395-7. · 6.17 Impact Factor
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ABSTRACT: Stearic acid as a coadsorbent, which has a low dipole moment and high solubility, retarded the rate of dye adsorption during the competitive anchoring process on the TiO(2) layer in dye-sensitized solar cells (DSCs), thereby increasing the content of strongly bound dye on the TiO(2) surface. This resulted in an approximately 25% improvement in both J(SC) and the power conversion efficiency of the DSCs, even for much lower dye coverage.
Chemical Communications 03/2011; 47(14):4147-9. · 6.17 Impact Factor
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Langmuir 01/2011; 27:14647–14653. · 4.19 Impact Factor
