Photo Electro Chemical performance evaluation of some natural dyes used in solar cells , DFT study and TD-DFT

Several natural dyes belonging to anthocyanin goups have been studied to evaluate their potential use in the dye sensitized solar cells (DSSCs). DFT/B3LYP 3-21G, DFT/B3LYP/ 631G, DFT/B3LYP/ 6-311G and TD-DFT as computational methods were used to calculate some parameters such as Egap, Voc and global electrophilicity using TiO2 as conduction band. Comparison between the three methods were done using statistical analysis to investigate the dye which is more efficient due to their photoelectrochemical performance, especially those of the Voc and global electrophilicity properties. The obtained results showed that the delphinidin pigment been the best one between the twenty five dyes used in this study.


Introduction
According to its durability characteristic, high conversion efficiency, ease of preparation and its clean environment, Dye-sensitized solar cells (DSSCs) were used as an alternative option of energy production (1)(2)(3)(4)(5) .DSSCs were first proposed by Grӓtzel et al (3) .It is the third generation photovoltaic device for low cost conversion of solar energy into electrical energy.
In DSSCs, the dyes plays an important role in harvesting solar energy and converts it to electrical energy with aid of a semiconducting photo anode.Researcher have focused on the easily available dyes extracted from natural sources as a photosensitizer because of its large absorption coefficients, low cost and its high degree of environmental friendliness (6)(7)(8)(9) .

Results and discussion
Both Voc and global electrophilicity were adopted as a measure of photosensitizer efficiency in this study using TiO2 as band gap semiconductor.The lower the global electrophilicity, the more efficient the solar cell (12) .The higher the Voc, the better light absorption and the higher electron mobility (13) .The results observed due to the different methods used, show that there are some differences in the efficiency sequence of the calculated compounds between these methods.To overcome this problem, statistical analysis were inserted in this study to determine the possible approximation.The sequence of values given by the iterative method was selected to be the suitable one for this purpose.Considering both factors (Voc and global electrophilicity), Table 3 and 4 with fig. 1 and 2 show that the delphinidin pigment represents the most efficient between the all dyes studied, owing to its highly iterative nature with the three method.

Conclusion
Between 25 natural dyes studied theoretically by DFT method using different basis sets, it has been found that the delphinidin pigment being the most potent option for using as efficient dye using in DSSCs owing to its highly iterative nature with the three method.

Photo
Photo Electro Chemical performance evaluation of some natural dyes used in solar cells, DFT study and TD-DFT Amir F. Dawood AL-Niaimi , Salah A. Jassim Humadi and Naba B. Ali

Fig- 1
Fig-1 Iterative analysis of Voc by different calculation methods Photo Electro Chemical performance evaluation of some natural dyes used in solar cells, DFT study and TD-DFT Amir F. Dawood AL-Niaimi , Salah A. Jassim Humadi and Naba B. Ali