We report the successful application of multiwall carbon nanotubes (CNTs) as electrocatalysts for triiodide reduction in a dye-sensitized solar cell (DSSC). Defect-rich edge planes of bamboolike-structure multiwall CNTs facilitate the electron-transfer kinetics at the counter electrode-electrolyte interface, resulting in low charge-transfer resistance and an improved fill factor. In combination with a dye-sensitized TiO2 photoanode and an organic liquid electrolyte, a multiwall CNT counter-electrode DSSC shows 7.7% energy conversion efficiency under 1 sun illumination (100 mW/cm(2), air mass 1.5 G). The short-term stability test at moderate conditions confirms the robustness of CNT counter-electrode DSSCs.

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Ordered mesoporous SnO2 with three-dimensional bicontinuous cubic mesostructure, high surface area, and crystalline frameworks was synthesized by the solvent-free infiltration of tin precursor in KIT-6 silica template and employed as a photoanode in dye-sensitized solar cells (DSSCs). It is shown that coating an ultrathin TiO2 or Al2O3 layer on mesoporous SnO2 photoanode greatly improves the open-circuit voltage, short-circuit current, and fill factor, leading to more than a 3-fold improvement in the energy conversion efficiency. The superior photovoltaic performance of surface modified mesoporous SnO2 photoanode is mainly the result of inhibited electron recombination caused by passivation of reactive surface states and increased dye loading. Control cells fabricated with conventional nanoparticle SnO2/TiO2 photoanode exhibit a similar trend but with about 30% lower energy conversion efficiency, which is mainly because of limitations due to low dye loading and poor light scattering.

Nanosize carbon powders were deposited on conducting glass substrate for counterelectrode application in dye sensitized solar cell (DSSC). Electrochemical impedance measurement shows that charge transfer resistance of carbon electrode in liquid electrolyte is 0.74Ωcm−2, which is two times less than that of screen printed platinum. Using such counterelectrode and dye sensitized TiO2 working electrode, DSSC was fabricated. Under one sun illumination (AM1.5, Pin of 100mWcm−2), carbon counterelectrode DSSC shows 6.73% overall energy conversion efficiency with good stability.