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For the 1st time, nonstoichiometric WO2.72 was used as a counter electrode (CE) in dye-sensitized solar cells (DSSCs). O-vacancy-rich WO2.72 nanorod bundles with notable catalytic activity for triiodide and thiolate redn. were prepd. The photovoltaic parameters of dye-sensitized solar cells (DSSCs) with WO2.72 nanorod bundles as CEs are superior compared with those of the WO3-based cells, and nearly the same as those of the precious metal Pt-based cells. In a noncorrosive org. redox couple, the performance of WO2.72 CEs is better than that of Pt and WO3 CEs in DSSCs.

The authors presented the solid-state synthesis of ZnO nanostructured building blocks for the fabrication of high efficiency quasi-solid Dye-Sensitized Solar Cells (DSSCs). Photoanodes composed of tiny nanosheets were sponge-like in construction, ensuring a high optical d. and better connections of the 2 sep. channels, 1 for the electron transport in the ZnO network and the other for the diffusion of redox couples in the electrolyte. The authors systematically revealed the effects of thermal-treating temps. on the microstructures and the elec. properties of the photoanode films as well as their performances in quasi-solid DSSCs. Also, by using a polymer gel electrolyte, the authors provided an effective strategy to simultaneously improve the photovoltaic conversion efficiency (PCE) and longterm durability. With the low-temp. treated photoanode films, devices achieved enhanced PCEs up to 6.46%, the highest for the ZnO quasi-solid DSSCs.

Zinc oxide (ZnO) hierarchical structures (HSs) have recently demonstrated notable photochem. and photovoltaic performances attributed to their nano/micro combined architectures. In this study, ZnO HSs were synthesized at room temp. using ultrarapid sonochem. This novel approach can effectively overcome deficiencies in the synthesis via traditional direct pptn. by promoting nucleation and accelerating diffusion. Only 15 min was needed to complete the formation of highly crystd. and uniformed HSs consisting of interconnected monocryst. nanosheets using sonochem. The formation of HSs through in situ observations was interpreted using a new mechanism based on oriented attachment and reconstruction. In the nonequil. synthesis system, thicker, porous, and coarse crystd. ZnO sheets were first constructed via oriented attachment of small-sized nanocrystals. After reconstruction, ultrathin, integrated, and monocryst. nanosheets were obtained. According to the two-dimensional nanosheets to three-dimensional HSs, the formation was much more sophisticated because repeated and parallel heterogeneous oriented attachments with reconstructions dominated the final morphologies of the HSs. The relationships between synthetic conditions and HSs structures were established. Based on the photoanodes in dye-sensitized solar cells (DSCs), the performances of these differently structured HSs were tested. HSs with densely assembled nanosheets exhibited better performances in photoelec. conversions. Systematic investigations were also carried out by selecting two representative HSs to demonstrate the crit. factors governing the optical and elec. properties of photoanodes. Finally, under AM 1.5 and 100 mW.cm-2 light irradn., high photoelec. conversion efficiencies of up to 6.42% were achieved. These results established a new record for quasi-solid ZnO-based DSCs.

TiC has been used as a counter electrode catalyst in place of Pt for triiodide redn. in dye-sensitized solar cells. Its catalytic activity can be comparable to that of Pt. The effect of the thickness of the TiC layer on the performance of the dye-sensitized solar cells was investigated by electrochem. impedance spectroscopy, cyclic voltammetry, and Tafel polarization measurements. We found that as the film thickness increased, the fill factor and short-circuit c.d. increased, which led to improved power conversion efficiency. When the TiC film was thicker than 20 μm, however, no significant continuous improvement in the catalytic activity was obsd. A high power conversion efficiency of 6.46% was obtained for the dye-sensitized solar cell by using a TiC counter electrode at the optimized film thickness, a value similar to that obtained with a Pt counter electrode.

We demonstrated that extracts from sea tangle can serve as a sensitizer, redox couple, as well as a counter electrode material, or even can be fabricated into an "all-natural solar cell". Especially, the carbon counter electrode from sea tangle has achieved a comparable performance with Pt, favorable for the cost-reduction of DSCs.