title: Dye-sensitized TiO2 solar cells using imidazolium-type ionic liquid crystal systems as effective electrolytes.
abstract: A novel ionic liquid crystal (ILC) system (C(12)MImI/I(2)) with a smectic A phase used as an electrolyte for a dye-sensitized solar cell (DSSC) showed the higher short-circuit current density (J(SC)) and the higher light-to-electricity conversion efficiency than the system using the non-liquid crystalline ionic liquid (C(11)MImI/I(2)), due to the higher conductivity of ILC. To investigate charge transport properties of the electrolytes in detail, the exchange reaction-based diffusion coefficients (D(ex)) were evaluated. The larger D(ex) value of ILC supported that the higher conductivity of ILC is attributed to the enhancement of the exchange reaction between iodide species. As a result of formation of the two-dimensional electron conductive pathways organized by the localized I(3)- and I- at S(A) layers, the concentration of polyiodide species exemplified by I(m)- (m = 5, 7, ...) was higher in C(12)MImI/I(2). However, as the increment of the concentration of polyiodide species is less than that of D(ex), the contribution of a two-dimensional structure of the conductive pathway through the increase of collision frequency between iodide species was proposed. Furthermore, a quasi-solid-state ionic liquid crystal DSSC was successfully fabricated by employing a low molecular gelator. Addition of the 5.0 g/L gelator to ILC improved light-to-electricity conversion efficiency through the increase of J(SC) due to the enhancement of the conductivity in C(12)MImI/I(2)-gel.
authors.affiliation: Material and Life Science, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita 565-0871, Japan.
authors.forename: Noriyo
authors.initials: N
authors.lastname: Yamanaka
authors.forename: Ryuji
authors.initials: R
authors.lastname: Kawano
authors.forename: Wataru
authors.initials: W
authors.lastname: Kubo
authors.forename: Naruhiko
authors.initials: N
authors.lastname: Masaki
authors.forename: Takayuki
authors.initials: T
authors.lastname: Kitamura
authors.forename: Yuji
authors.initials: Y
authors.lastname: Wada
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Watanabe
authors.forename: Shozo
authors.initials: S
authors.lastname: Yanagida
mesh_terms: D004396:Coloring Agents / Q000737:chemistry*; D003460:Crystallization; D004058:Diffusion; D004553:Electric Conductivity; D011211:Electric Power Supplies; D004573:Electrolytes / Q000737:chemistry*; D007093:Imidazoles / Q000737:chemistry*; D052578:Ionic Liquids / Q000737:chemistry*; D015394:Molecular Structure; D012680:Sensitivity and Specificity; D012993:Solar Energy; D013696:Temperature; D014025:Titanium / Q000737:chemistry*
chemical_list: D004396:Coloring Agents; D004573:Electrolytes; D007093:Imidazoles; D052578:Ionic Liquids; C009495:titanium dioxide; D014025:Titanium