Enhanced photoelectrochemical performance of ZnO electrodes sensitized with N-719

To improve dye-loading in photoanodes, microstructure of ZnO films was modified through the formation and pyrolysis of layered hydroxide zinc acetate (LHZA) grown in a methanolic solution of zinc acetate dihydrate. Appropriate annealing treatments for the films led to the formation of mesoporous microstructure with an average pore diameter of 12 nm. It was demonstrated that loading of N-719 in the ZnO films was successful without influence of protons in solutions, as evidenced by a large dye amount of 1.4 × 10–7 mol/cm2, and hence a high short-circuit photocurrent density of 12.6 mA/cm2. Sandwich-type dye-sensitized solar cells using the present ZnO/N-719 photoanode exhibited a conversion efficiency as high as 4.1% (AM-1.5, 100 mW/cm2).