**Author notes**

On leave from Chemistry Department, Assiut University

*Excited-State Dynamics of Organic Dyes in Solar Cells DOI: http://dx.doi.org/10.5772/intechopen.94132*

*Solar Cells - Theory, Materials and Recent Advances*

However, upon adding I3

the DSSC efficiency.

**6. Conclusion**

**Figure 12.**

**Author notes**

− , I−

*and complexes of D149 with iodide, and full electrolyte.*

correlating with the output efficiency of the DSSC.

On leave from Chemistry Department, Assiut University

traditional iodide electrolyte used in various DSSC sets [45]. For the case of D149/ TiO2, slower electron injection and recombination processes have been observed.

*Effect of chemical interactions between the D149 organic dye and the redox couple electrolyte (Iodide, iodine, tri-iodide) on the electron dynamics of D149 dye on mesoporous TiO2, the rise of the signal is due to electron injection, while the signal decay is due to the electron recombination, readapted from reference [15]. (A) Comparison between D149 and complexes of D149 with tri-iodide, and iodine. (B) Comparison between D149* 

ca. 100 fs, and more importantly the electron recombination was increased dramatically, due to the adsorbed complexes species on the surface [15]. Thus, the chemical interactions between the chemical substances should be considered upon optimizing

Although the DSSC shows promising results with respect to low-cost and moderate efficiency in comparison with inorganic semiconductor solar cells, the ongoing processes in DSSC are quite complex and lots of studies are required to increase the output efficiency. In this chapter, we highlighted the fact that organic dyes have many excited state processes that have been overlooked in the past. Most of these processes showed detrimental effects on the overall performance of the DSSC. However, other exited state processes, such as the formation of TICT state, illustrated that high efficiency can also be attained through the excited state dynamics of the adsorbed dye. Understanding the dye's excited state processes will allow for fine tuning of such processes, via the chemical synthesis of organic dyes,

, or I2, the electron injection process was much faster of

**376**
