Functional Electrode Materials For Dye-sensitized Solar Cells

Dye-sensitized solar cells (DSSCs) have drawn much attention for its simple fabrication, low cost of manufacture and high photoelectric conversion efficiency. The development of novel type of electrode material provides a new approach to the enhancement of the photovoltaic performance, the cost reduction and the development of the practical cell device. The research contents are conculed as follows:Highly ordered mesoporous carbon (OMC) with surface area of1044m2/g was prepared by tri-constituent co-asssembly method. And it was applied in DSSCs as counter elecrode. It was found that OMC electrode could provide more electrochemical surface area for the reduction of I3-compared with conventional carbon black counter electrode for its much larger surface area. So, the DSSC based on OMC counter electrode has much better performance than the ones employing conventional carbon black counter electrode. And its short-circuit current density can reach13.92mA cm-2, and the conversion efficiency can reach as high as6.51%. In addition, the fabrication cost of OMC electrode is much lower compared with the conventional Pt counter electrode, so it is a kind of high efficiency low cost counter electrode.Polypyrrole (PPy) nanotube with diameter of100nm was prepared by template method and assembled into flexible PPy membrane with the thickness of about180μm. Because the membrane has large surface area, a certain thickness and good permeability, it benefits the penetration of the electrolyte and the reduction of the I3-when it’s applied as counter electrode of DSSCs. And the photoelectric conversion efficiency of the device based on the PPy membrane can reach5.27%, which is about84%of the cell based on the conventional Pt/FTO counter electrode.The absorption onset of dye used in DSSCs is about750nm, so all the photons with the energy less than1.65eV can’t be utilized, which means that more than50%light energy is wasted. In order to make full use of this part of energy and enhance the conversion efficiency of DSSCs, the concept of introducing intermediate band into DSSCs was proposed for the first time. For the convenience of calculations, the limit conversion efficiency of the intermediate band solar cell based on TiO2was calculated. And the result showed that the limit efficiency can reach42%and50%, respectively, when one or two intermediate band was induced in the band gap of TiO2. The concept provided a new approach to the development of DSSCs.Trace amount Mo-doped TiO2nanocrystal film was prepared by hydrothermal method and applied as photoanode in DSSCs. It was comfirmed that moderate doping of Mo benefited the enhancement of the electrode lifetime and the transport by open circuit voltage decay test and electrochemical impedance spectroscopy test. As a result, the short circuit current density and photoelectric conversion efficiency was enhacned significantly. The photovoltaic performance of the cell was the best when the doping concentration was20ppm. However, the deep mechanism of trace amount doping in DSSCs still need further study and analysis.