Quasi-Solid Dye Sensitized Solar Cell with Straight Ion Paths

Quasi-solid dye sensitized solar cells (QDSC) with straight ion paths are reported. The cell consists of anodic oxidation Al 2 O 3 films. Ionic liquid-type electrolyte is filled in the straight nanopores and they are sandwiched between a counter electrode and a TiO 2 electrode. Even when electrochemically inactive Al 2 O 2 wall occupies 50% of the electrolyte layer, the I - 3 diffusion coefficient and solar cell performance are the same as those without the Al 2 O 3 layers. This contrasts the results of cells filled with the mixture of Al 2 O 3 nanoparticles and ionic liquid type electrolytes, where random ion paths are expected. In addition, when the inner wall of anodic oxidation Al 2 O 3 films is chemically modified with long alkyl groups bearing methylimidazolium moieties, the increase in photovoltaic performance is observed. This is explained by the existence of ion paths along aligned methylimidazolium moieties in the surface-modified Al 2 O 3 films, where I 2 (I - 3 ) species are concentrated. The swift apparent Ij diffusion coefficient is explained by Grotthuss mechanism. Because the I 2 species are concentrated in the straight pore of Al 2 O 3 layers, the concentration of I 2 (I - 3 ) species in TiO 2 layers is reduced relatively. This increases light penetration depth at around 400 nm in the porous TiO 2 layer and improves incident photon-to-current efficiency at around 400 nm. The hybrid electrolyte systems containing both of concentrated I 2 (I - 3 ) in a porous Al 2 O 3 layer and low concentration portions in nanopores in TiO 2 are proposed to increase ionic liquid-type QDSC.