Development of new counter electrode materials is vital for commercialization of efficient dye-sensitized solar cells (DSCs) process. Research on DSCs has been focused mainly on using platinum as counter electrode, which makes them expensive. In this paper, we report DSCs fabricated with high surface area mesoporous carbon thin film with uniform spherical particles as counter electrode. An overall light-to-electricity efficiency as high as 7.6% has been achieved under illumination of air mass (AM) 1.5 sunlight (100？mW/cm2). In comparison with activated carbon, high surface area mesoporous carbon shows superior performance. Our results show that mesoporous carbon with high specific surface area and uniform pore size distribution proved to be better efficient electrode material for DSCs. 1. Introduction Environmental concerns and global energy demand have triggered the interest in development of renewable energy especially solar energy. Conventional silicon-based solar cells are large-scale, single-junction devices, and very high percentage of photovoltaic production comes from these solar cells [1, 2]. However, cost of these solar cells made them not economical compared with other power-generating methods. In recent years, DSCs have attracted a great deal of attention due to its simple fabrication and low production cost. DSCs are composed of porous nanostructured oxide film with adsorbed dye molecules as a dye-sensitized anode, an electrolyte containing iodide/triiodide redox couple, and a platinized fluorine-doped tin oxide (FTO) glass as the counter electrode [3–5]. For further reduction of production cost of DSCs, development of new electrode material to replace platinum counter electrode is highly desirable. Mesoporous carbon with very high surface area and uniform pore size distribution has emerged to be the best candidate in this respect. In addition, porous carbons have attracted much attention due to their potential applications in catalysis, adsorption, storage of natural gas, separation process, and electric double-layer capacitors [6–10]. Several different methods have been developed to synthesize mesoporous carbons. Among them, template synthesis method [11, 12] has been extensively used since the obtained material possesses uniform and interconnected pores. This synthetic technique involves impregnation of silica templates with an appropriate carbon source, carbonization of carbon precursor, and subsequent removal of silica. After the discovery of ordered mesoporous carbon materials by Ryoo et al. using mesoporous silica as a template and
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