Dye-sensitized solar cell (DSSC) is a device that converts solar energy into electric energy. Dye-sensitized solar cell (DSSC) can make full use of renewable new energy sources, having a broad application prospect. First, under the irradiation of light, the dye molecules are excited and turn into the excited state. Second, the excited state dye molecules rapidly injected electrons into the nano TiO2 conducting band. Then, the excited dye molecules are reduced by electrolyte. Finally, taking electrons from the external circuit, the electrolyte in turn can be reduced.
Figure 1. The diagram of DSSC operating principle.
Figure 2. Dye-sensitized solar cell applied in modern glass curtain building.
There are many kinds of materials that make up dye-sensitized solar cell, the most important components are listed as below.
1. Liquid electrolytes: Liquid electrolytes mainly include I-/I3-, Br/Br2, SCN-/(SCN)2 and binary ionic liquid systems of PMII and EMIDCA.
2. Quasi solid electrolytes：Quasi solid electrolytes mainly include small molecule gel electrolyte and polymer gel electrolyte.
3. Solid electrolytes: The most widely studied solid electrolytes are organic hole transporting materials and inorganic P-type semiconductor materials. Solid electrolytes can solve the problem of electrolyte volatilization, but the poor contact with nano-semiconductor electrode affects the charge transmission.
1. Metal complex photosensitizer: The most frequently used metal complexes are ruthenium polypyridine complexes. In addition, porphyrin dyes are also a group of metal complex photosensitive agents mainly including porphyrin dyes with Zn coordination and Cu coordination.
Figure 3. Examples of metal complex photosensitizer.
2. Pure organic photosensitizer: Pure organic photosensitizer has become a hotspot in the field of photosensitizer due to its advantages of easy modification and high molar absorption coefficient. These dyes mostly belong to the structure of donor-π-acceptor, and the most studied dyes include coumarins, indoles and carbazoles.
Figure 4. An example of pure organic photosensitizer.