# Light Harvesting and Optical-Electronic Properties of Two Quercitin and Rutin Natural Dyes
## Results and Discussion
### Fourier Transforms Infrared Spectrum  
Figure 2a presents the experimental FT-IR spectrum of Q. The main characteristic peaks of Q are distributed in the frequency range of 700-1700 cm\({}^{-1}\), and there are three obvious characteristic peaks within the frequency range of 1700-4000 cm\({}^{-1}\). The corresponding characteristic peaks are 822 cm\({}^{-1}\), 1037 cm\({}^{-1}\), 1124 cm\({}^{-1}\), 1542 cm\({}^{-1}\), 1605 cm\({}^{-1}\), 1808 cm\({}^{-1}\), 3267 cm\({}^{-1}\), and 3686 cm\({}^{-1}\) respectively. The theoretical simulated FT-IR spectrum of V-Q is exhibited in Figure 2c, and the characteristics are in the frequencies of 816.97 cm\({}^{-1}\), 982.55 cm\({}^{-1}\), 1192.30 cm\({}^{-1}\), 1546.03 cm\({}^{-1}\), 1647.84 cm\({}^{-1}\), 1709.63 cm\({}^{-1}\)3285.78 cm\({}^{-1}\), and 3578.89 cm\({}^{-1}\), respectively. The first three the strongest peaks in the theoretical simulation are in the frequencies of 3578.89 cm\({}^{-1}\), 1709.63 cm\({}^{-1}\), and 1647.84 cm\({}^{-1}\), which are in accordance with the frequencies of 3686 cm\({}^{-1}\), 1808 cm\({}^{-1}\), and 1605 cm\({}^{-1}\) in the experiment. Figure S3 lists the labels of V-Q. As to the theoretical vibration, the strongest vibration peak is mainly formed by the vibration of O\({}_{28}\)-H\({}_{49}\). The second strongest vibration peak is formed by the vibrations of benzene ring (C\({}_{1}\)-C\({}_{2}\)-C\({}_{3}\)-C\({}_{4}\)-C\({}_{5}\)-C\({}_{6}\)) and by O\({}_{30}\)-H\({}_{51}\). The third strongest vibration peak is mainly formulated by the benzene ring vibrations (C\({}_{1}\)-C\({}_{2}\)-C\({}_{3}\)-C\({}_{4}\)-C\({}_{5}\)-C\({}_{6}\), C\({}_{11}\)-C\({}_{12}\)-C\({}_{17}\)-C\({}_{16}\)-C\({}_{15}\)-C\({}_{14}\)).  
Figure 2b shows the experimental FT-IR spectrum of R. The main characteristics peaks of R are distributed in the frequency range of 500-1700 cm\({}^{-1}\), and there are four major characteristic peaks within the frequency range of 1700-4000 cm\({}^{-1}\). The corresponding characteristic peaks are in the frequencies 805 cm\({}^{-1}\), 952 cm\({}^{-1}\), 1070 cm\({}^{-1}\), 1213 cm\({}^{-1}\), 1655 cm\({}^{-1}\), 1772 cm\({}^{-1}\), 3011 cm\({}^{-1}\), 3380 cm\({}^{-1}\), and 3715 cm\({}^{-1}\), respectively. The theoretical simulated FT-IR spectrum of S-R appears in Figure 2d. The characteristics are in the frequencies of 804.06 cm\({}^{-1}\), 958.61 cm\({}^{-1}\), 1076.67 cm\({}^{-1}\), 1226.70 cm\({}^{-1}\), 1677.49 cm\({}^{-1}\), 1716.08 cm\({}^{-1}\), 3118.63 cm\({}^{-1}\), 3219.61 cm\({}^{-1}\), and 3730.73 cm\({}^{-1}\), respectively. The three strongest peaks in theoretical simulation are in the frequencies of 1266.70 cm\({}^{-1}\), 1677.49 cm\({}^{-1}\), and 1716.08 cm\({}^{-1}\), which are in accordance with the frequencies of 1213 cm\({}^{-1}\), 1655 cm\({}^{-1}\), and 1772 cm\({}^{-1}\) in the experiment. Figure S3 shows the labels of V-R. The two strongest vibration peaks are mainly formed by the vibration (C\({}_{18}\)-C\({}_{19}\)-C\({}_{24}\)-C\({}_{23}\)-C\({}_{22}\)-C\({}_{21}\)). The third strongest vibration peak is primarily formed by vibration of C\({}_{17}\)=O\({}_{25}\). When compared with the peaks of theoretical simulation of V-Q and  
Figure 2: The experimental Fourier transforms infrared (FT-IR) spectrum of Q and R shown in (**a,b**); The theoretical FT-IR spectrum of V-Q and V-R shown in (**c,d**).  
V-R and the experimental data of Q and R, it can be concluded that the theoretical calculated data can be well conformed with the experimental data.