# Light Harvesting and Optical-Electronic Properties of Two Quercitin and Rutin Natural Dyes
## 4 Conclusions  
In this paper, we investigated the photoelectric properties of two molecules in the experiment, showing that S-Q has a better \(\eta\) of 2.151% than S-R of 0.713%. For explaining the performance difference, geometry and electronic structures, absorption and fluorescence properties, molecular descriptor parameters, polarizability, and hyperpolarizability, PDOS, ESP, CDD, and FMOs of two molecules were investigated on DFT and TDDFT level. The theoretical simulation shows that S-Q has lower energy gap, higher HOMO, LHE, W and W\({}^{+}\), longer \(\tau\), larger EA, ESP values, and a planar structure, which demonstrates that S-Q needs less energy to be excited, it can harvest more sunlight, has a longer  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Dyes** & **LHE** & \(E_{OX}^{dye}\) & \(E_{OX}^{dye}\) & \(\Delta G^{inject}\) \\ \hline S-Q & 0.603 & 5.834 & 2.347 & \(-\)1.653 \\ S-R & 0.563 & 5.907 & 2.227 & \(-\)1.773 \\ \hline \hline \end{tabular}
\end{table}
Table 6: The driving force of electron injection \(\Delta G^{inject}\) (in eV) for S-Q and S-R.  
time for transfer of electrons, has a better energetic stability to attract electrons and a better electron donating ability for forming photocurrents, and it has a higher tendency to react with electrolytes for the regeneration of dyes when compared to S-R. These key factors tell us that S-Q has a higher photoelectric properties than S-R, and S-Q is an excellent sensitizer.  
The following are available online at [[http://www.mdpi.com/2076-3417/9/12/2567/s1](http://www.mdpi.com/2076-3417/9/12/2567/s1)]([http://www.mdpi.com/2076-3417/9/12/2567/s1](http://www.mdpi.com/2076-3417/9/12/2567/s1)), Figure S1: The schematic structure of DSSC devices. Figure S2: The optimized ground state structures of S-Q and S-R. Figure S3: The labels of S-Q and S-R corresponding to the FT-IR spectrum. Figure S4: Frontier molecular orbitals of S-Q and S-R. Figure S5: The CDD pictures of S-Q and S-R. Figure S6: The composition of Q (A, B, C represents the group of 3,5,7-trihydroxy-4H-chrom-4-one; pyrocatech; 2-methyl-tetrahydro-2H- pyram-3,4,5-triol, respectively) and R (A,B,C represents the group of 2,2'-(1,2-Phenylenebis(oxy)diethanol;3,5-dihydroxy-7-(2-hydroxyethoxy)-2-methyl-4H-chrom-4-one;2-methyl-6-((3,4,5-trihydroxytetrahydro-2-H-pyram-2-yl)methoxy) tetrahydro-2-H-pyram-3,4,5-triol respectively). Table S1: Selected bond lengths (A) and dihedral angles(\({}^{\circ}\)) of R and Q in phase of vacuum and solvent. Table S2: The calculated PDOS of S-Q and S-R. Table S3: The calculated NBO of S-Q and S-R. Table S4: The dipole moments \(\mu\) (D), the polarizability \(\alpha\) (a.u.), the average polarizability \(\alpha\) (esu), the anisotropy of the polarizability \(\alpha\) (esu), and the first hyperpolarizability \(\beta\)tot (esu) of S-Q and S-R. Table S5: Charge transfer distance (DCT), overlap extent (Sr), \(t\) and H index derived through electron and hole analysis. Table S6: The experimental stokes shift of Q and R in three different solvents (water, dimethyl sulfoxide (DMSO), methanol). Table S7: The theoretical calculated stokes shift of Q and R. Table S8: The fluorescent lifetime of S-Q and S-R. Table S9: The I-V parallel experiments of S-Q and S-R.  
Conceptualization: Y.L., M.Z. and R.S.; Funding acquisition: Y.L.; Investigation and data analysis: D.Z. and Q.L.; Software: Y.L. and M.Z.; Writing--original draft: [PERSON]; Writing--review & editing: [PERSON] and Y.L.  
This work was supported by the Fundamental Research Funds for the Central Universities (2572018 BC24), Chengdong Scholar Training Program, Heilongjiang Postdoctoral Grant (LBH-Z15002), the China Postdoctoral Science Foundation (2016M590270) and the National Natural Science Foundation of China (Grant Nos. 11404055 and 11374353).  
The authors declare no conflict of interest.