Dye-sensitized solar cells (DSCs) offer the possibilities to design solar cells with a large flexibility in shape, color, and transparency. DSC research groups have been established around the worl ...

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Dye-Sensitized Solar Cells

Functional π-Gelators and Their Applications

Room-temperature ionic liquids (RTILs) based on 1-butyl-3-methylimidazolium ([bmim]) with a variety of fluorinated anions were prepared, and the thermal behavior, density, viscosity, self-diffusion coefficients of the cations and anions, and ionic conductivity were measured over a wide temperature range. The temperature dependencies of the self-diffusion coefficient, viscosity, ionic conductivity, and molar conductivity have been fitted to the Vogel−Fulcher−Tamman equation, and the best-fit parameters for the self-diffusion coefficient, viscosity, ionic conductivity, and molar conductivity have been estimated, together with the linear fitting parameters for the density. The self-diffusion coefficients determined for the individual ions by pulsed-field-gradient spin−echo NMR method exhibit higher values for the cation compared with the anion over a wide temperature range, even if its radius is larger than that of the anionic radii. The summation of the cationic and anionic diffusion coefficients for the RT...

Physicochemical Properties and Structures of Room Temperature Ionic Liquids. 1. Variation of Anionic Species

Toxicity of nanoparticles of CuO, ZnO and TiO2 to microalgae Pseudokirchneriella subcapitata

Poly(ionic liquid)s: An update

C‐axis oriented YBa2Cu3O7−x thin films are conventionally obtained on polycrystalline substrates, but a‐ and b‐axes are randomly distributed. Due to the weak links at the high‐angle grain boundaries in the a–b plane, the critical current density (Jc) are comparatively low, from 103 to 104 A/cm2 (77 K, 0 T), and the Jc decreases in magnetic field in a manner similar to bulk YBa2Cu3 O7−x samples. To reduce weak links at the high‐angle grain boundaries, biaxially oriented buffer layers of yttrium stabilized zirconia (YSZ) were formed on polycrystalline, Ni‐based alloy by ion‐beam assisted deposition (IBAD), and subsequently the a–b plane aligned YBa2Cu3 O7−x film was deposited by laser ablation. Jc of 2.5×105 A/cm2 (77 K, 0 T) and 2.2×104 A/cm2 (77 K, 8.0 T) were obtained. A new method to prevent intergranular weak links has been developed for potential applications using practical polycrystalline substrates.

In‐plane aligned YBa2Cu3O7−x thin films deposited on polycrystalline metallic substrates

Room temperature ionic liquids have been used as electrolytes to investigate the performance and the characteristics in dye-sensitized solar cells (DSSCs). The ionic liquids used are 1-ethyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide (EMImTFSI), 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF4), 1-butyl-3-methylimidazolium hexafluorophosphate (BMImPF6), 1-ethyl-3-methylimidazolium dicyanamide (EMImDCA), and 1-butylpyridinium bis(trifluoromethane sulfonyl)imide (BPTFSI), in which 1-ethyl-3-methylimidazolium iodide (EMImI) and I2 are dissolved as a redox couple. The structure and the property greatly influence the DSSC performances. Especially, the photocurrents are affected by the ionic conductivity (viscosity) and charge transport by the exchange reaction between the iodide/tri-iodide redox couple. EMImDCA is specific in terms of enhancement of the open-circuit voltages. The photo-energy conversion efficiency of DSSCs with EMImDCA under 100 mW cm−2 can be optimized up to 5.5%, when [I−] + [I3−] = 2 M and [I−]:[I2]=10:1 with the addition of 4-t-butylpyridine and LiI.

High performance dye-sensitized solar cells using ionic liquids as their electrolytes

In this study, an effect of addition of nanoparticles into a dye-sensitized solar cells (DSCs) ionic liquid electrolyte was explored. Carbon nanotubes, other carbon nanoparticles and titanium dioxide nanoparticles were dispersed individually into a 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIm-TFSI) ionic liquid electrolyte by grinding. It was centrifuged to form an ionic nanocomposite gel electrolyte. The dispersion of nanoparticles resulted in a substantial increase in their viscosity. Their electric conductivity increased as well. Notable effects were obtained in photocurrent density and voltage measurements of the DSC assembled with them. Energy conversion efficiency of them was significantly improved and increased compared with a DSC using a bare ionic liquid electrolyte.

Improved dye-sensitized solar cells using ionic nanocomposite gel electrolytes

Biaxially aligned YBa2Cu3O7−x (YBCO) thin films were produced on polycrystalline Ni‐based alloy, by using biaxial yttria‐stabilized‐zirconia (YSZ) intermediate layers formed by off‐normal ion‐beam‐assisted deposition Most explicit in‐plane alignment was obtained when the YSZ layer formed with the beam‐incident angle of 55° from substrate normal Jc‐B characteristics and angular dependence of Jc on the magnetic field were measured 50×105 and 55×104 A/cm2 were obtained at 77 K with 0 and 8 T, respectively The distribution of misorientation angles of in‐plane a and b axes between YBCO grains was evaluated by both x‐ray pole figure measurement and planar observations of transmission electron microscopy 50% of the grains had the misorientation angles restricted within ±5° From the image of dislocations, the elastic strains at grain boundaries were estimated to be relaxed with lower misorientation angle The high‐Jc properties are understood to be obtained by the current paths through low‐angle grain bou

Structural and transport properties of biaxially aligned YBa2Cu3O7−x films on polycrystalline Ni‐based alloy with ion‐beam‐modified buffer layers

New transparent conductive oxide (TCO) films, fluorine-doped tin oxide (FTO) films coated on indium–tin oxide (ITO) films, were developed for dye-sensitized solar cells (DSC). These transparent conductive films were prepared by a spray pyrolysis deposition (SPD) method at a substrate temperature of 350 °C in ITO and 400 °C in FTO. For ITO deposition, an ethanol solution of indium(III) chloride, InCl 3 ·4H 2 O, and tin(II) chloride, SnCl 2 ·2H 2 O (Sn/(In+Sn), 5 at.%) was sprayed on a TEMPAX #8330 glass substrate (100×100×1.1 mm 3 ). After the deposition of ITO, FTO films were consecutively deposited for protecting oxidation of ITO films. FTO deposition was carried out by an ethanol solution of tin(IV) chloride, SnCl 4 ·5H 2 O within the saturated water solution of NH 4 F. These films achieved the lowest resistivity of 1.4×10 −4  Ω cm and the optical transmittance of more than 80% in the visible range of the spectrum. The electrical resistance of these films increased by less than 10% even though exposed to high temperatures of 300–600 °C for 1 h in the air. The DSC composed of the films were fabricated to confirm their availability. The films were of large size, 100×100 mm 2 . The DSC were made by conventional method. As a result, energy conversion efficiency of η =3.7% was obtained.

Nobuo Tanabe

Papers

In‐plane aligned YBa2Cu3O7−x thin films deposited on polycrystalline metallic substrates

High performance dye-sensitized solar cells using ionic liquids as their electrolytes

Improved dye-sensitized solar cells using ionic nanocomposite gel electrolytes

Structural and transport properties of biaxially aligned YBa2Cu3O7−x films on polycrystalline Ni‐based alloy with ion‐beam‐modified buffer layers

FTO/ITO double-layered transparent conductive oxide for dye-sensitized solar cells