Crystalline Matrix of Mesoporous TiO₂ Framework for Dye-Sensitized Solar Cell Application

In the present study, a well-ordered columnar porous TiO₂ matrix is designed via inverted triblock copolymers self-assembly and introduced as a photoanode for dye-sensitized solar cells (DSSCs). The inverted triblock copolymer, polystyrene-<i>b</i>-poly­(ethylene oxide)-<i>b</i>-polystyrene, with the hydrophobic polystyrene segments at both ends of a hydrophilic poly­(ethylene oxide) chain is synthesized by atom transfer radical polymerization. These reverse-featured triblock copolymers allow facile stacking to 3-dimensional (D) columnar porous matrix from 2-D porous film via hydrophobic–hydrophilic interaction. A 3-D matrix with well-ordered cylindrical pores is favorable to current flow by providing a direct electron pathway. DSSCs with a 3-D matrix of 2 μm thickness show an enhanced photocurrent density of 8.1 mA cm^–2 and higher photoconversion efficiency of 4.23% compared with those of TiO₂ nanoparticle photoelectrode under the illumination of 1 sun (AM 1.5 G 100 mW cm^–2). For the first time, we address that a 3-D metal oxide electrode with columnar pore is demonstrated via reverse-featured triblock copolymer and analyzed with relationships between their structural features and impedance spectroscopy for DSSCs