Summary of electrochemical technology
in dye-sensitized solar cells
Dye-sensitized solar cell (DSC) is a promising alternative solar cell to the conventional silicon solar cell due to several advantages. Development of large scale module is necessary to commercialize the DSC in the near future.And electrochemical technology is played a significant role in the development of DSC.These electrochemical methods is widely researched by scientists from different countries.
Electropolymerization ; dye-sensitized solar cell ; Electrodeposition
In light-collecting devices, such as solar cells, color sensors, etc., the device ...view middle of the document...
However, there are some severe problems to use the liquid electrolytes in DSSCs such as leakage and evaporation which are critical and affect the long term stability for practical applications.
electrochemical polymerization dye sensitization (ECDS) method
In recent years, ZnO nanorods (ZNR) have been prepared by several techniques such as vapor–liquid–solid (VLS), chemical vapor deposition (CVD) , electron beam evaporation (EBE), flame spray pyrolysis, hydrothermal method, and electrochemical deposition. The main interest in using electrochemical deposition is to avoid the high temperature, rigorous condition and complex operation required for VLS, CVD, EBE, and spray pyrolysis. Therefore, this method of preparation is more convenient and economic for large-scale preparation of ZNRs.
Thanks to the efforts reported on electrodeposition of ZNRs, the influence of the parameters on the geometry is now nicely controlled. The influence of the electrodeposition potential, the growth temperature, the zinc concentration, the electrolyte concentration, and the amount of charge deposited has been reported, notably by Peulon and Lincot, Elias et al., and Guo et al.. The use of a buffer layer has been reported by Tena-Zaera et al., with an increase of density of the ZNRs, while the diameter remains stable as a result.
In DSSCs, nanorod networks are efficient for transferring both holes and electrons sometimes called “electron/hole highways.” However, their low surface area makes them poor candidates for photoelectrodes in light-collecting devices.
Effort has already been made into the investigation of zinc oxide design in a nanoscale from electrochemistry: apart from nanorods, structures such as flowers, nanocoils, cauliflowers, microsphere, nanotubes arrays, sponge, etc., have been obtained. Hierarchical structures in shape of dendrites have also been reported.
Best results in terms of surface area were obtained for a ZnO/Eosin hybrid with sponge-like structure at a nanoscale level, also called nanoporous structure (NPS). A maximum of roughness factor up to 400 could be obtained on a 3 µm thick film. For comparison, TiO2 nanoparticles films reach a roughness factor up to 1000 for a thickness of 10 µm. Yoshida et al.and Minoura and Yoshida could achieve an efficiency up to 5.6% when used that material as a photoelectrode in DSSC.
The aim of this study is to combine the performances of both ZNRs and ZnO/Eosin hybrid material. Thus, a new structure has been investigated that mixes the nanoporous ZnO structure grown on ZNRs used as highways for electrons. The space between two hierarchical structures would make the way of the electrolyte to the dye easier and would therefore act as a highway for holes (figure in the abstract).
The present paper first presents results on ZNR geometry depending on the deposition conditions. Different geometries are then used for the hierarchical structure. We demonstrated that epitaxial growth of the NPS on...