Dye-sensitized solar cells (DSSC) are widely used in integrated circuits, electronic components, and electronic light-emitting diodes due to their advantages of light weight, low cost, safety and environmental protection, and simple industrial technology. Dye sensitizers are the key components for DSSC to achieve high photoelectric conversion efficiency. The most commonly used sensitizers are metal complexes. Active redox reactions in metal complexes mainly include the oxidation of central ions and the reduction of ligands. The choice of ligands directly affects the properties of metal complex dye sensitizers and thus the efficiency of DSSC devices. In metal complexes, the electron-donating effect, steric configuration and self-structure of ligands all affect the performance of dye sensitizers. The stronger the π electron accepting ability of the ligand, the weaker the σ electron donating ability, and the easier the reduction reaction occurs. The more favorable the configuration of the complex formed by the ligand is for the average distribution of the central ion charge, the easier the reduction reaction will occur. Therefore, the photoelectric conversion efficiency of metal complex dye sensitizers can be regulated by changing the type and structure of the ligands, thereby obtaining DSSC devices with excellent photoelectric properties.
Figure 1. Chemical structures of some metal ligands