This study investigates the applicability of a counter electrode with a P-type semiconductor oxide (such as NiO) on a dye-sensitized solar cell (DSSC). The counter electrode is fabricated by depositing an NiO film on top of a Pt film, which has been deposited on a Fluorine-doped tin oxide (FTO) glass using an ion-sputtering coater (or E-beam evaporator), using a simple spin coating method. This study also examines the effect of the average thickness of T i O 2 film deposited on a working electrode upon the power conversion efficiency of a DSSC. This study shows that the power conversion efficiency of a DSSC with a Pt(E)/NiO counter electrode (4.28%) substantially exceeds that of a conventional DSSC with a Pt(E) counter electrode (3.16%) on which a Pt film was deposited using an E-beam evaporator. This result is attributed to the fact that the NiO film coated on the Pt(E) counter electrode improves the electrocatalytic activity of the counter electrode. 1. Introduction Solar power is the most notable among renewable energy resources because of its low environmental impact and global availability. Among alternative forms of solar cells, dye-sensitized solar cells (DSSCs), as proposed by O’Regan and Gr？tzel [1], have attracted considerable interest since 1991 because of its properties, such as low production cost and low environmental impact during fabrication [2, 3]. In the past few years (2006–2009), several methods have been utilized in modifying the structure of a working electrode (TiO2 electrode) to improve the performance of DSSCs [4–22]. Novel sensitizers were synthesized and applied in DSSCs to promote the absorption of the visible spectrum [3, 23–29]. Novel electrolytes were proposed to prevent leakage of the electrolyte or to increase the lifetime (or performance) of DSSCs [30–35]. Moreover, a quasisolid DSSC with straight ion paths based on an anodically oxidized Al2O3 film, which was full of nanopores from one side of the film to the other, was presented [36]. The counter electrode is an equally important component of the DSSC. The role of the counter electrode is to transfer electrons from an external circuit to the tri-iodide and iodine in the redox electrolyte. Currently, a layer of platinum (Pt) coated on a transparent conducting oxide (TCO) substrate is widely used as a counter electrode in DSSCs. Besides platinum (Pt), carbon materials (such as graphite powder and carbon black [37, 38], hard carbon spherule [39], single-walled carbon nanotubes [40], multiwalled carbon nanotubes [41], and nanosized carbon powder [42, 43]) have been used
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