In dye-sensitized solar cells (DSSCs) fabricated with azobenzene and azulene derivatives as the photosensitizing dyes, the replacement of the conventional I-3(-)/I- redox mediator with Br-3(-)/Br- redox mediator possessing more positive redox potential has been examined to improve open-circuit photovoltages (V-oc) of the cells. The cells with the Br-3(-)/Br- redox mediator exhibited high V-oc of similar to 0.8 V, resulting in higher light-to-electric energy conversion efficiencies (eta) than the cells with the I-3(-)/I- redox mediator by a factor of 1.7 under the simulated sunlight irradiation (AM-1.5G, 100 mW cm(-2)). The results indicate a high potential of the Br-3(-)/Br- redox mediator in DSSCs.