Theoretical and experimental study on spectra, electronic structure and photoelectric properties of three nature dyes used for solar cells

Natural red 25 is investigated by FT-IR, UV-Vis spectrum, current-voltage characteristics under different pH values. The molecular geometry and frontier molecular orbitals are calculated using the Hartree-Fock (HF) and density functional theory (DFT) with 6-31G(d) basis set. Applying the TD-DFT method, the absorption spectrum is simulated in gas phase and ethanol solvent, and the calculated results are compared with the experimental data for Natural red 25. The dipole moment (mu), ionization energy (I), electron affinity (A), electronegativity(chi), hardness (eta), softness (S), electrophilicity index (phi) and total molecular energies (E-TOTAL]) of Natural red 25 are calculated via HF/6-31G(d) and DFT/6-31G(d) methods, which are all correlated with the HOMO and LUMO energies. In addition, photoelectric properties of 5-Aminofluorescein and 6-Aminofluorescein are measured and calculated, which have same molecular formula (C20H13NO5) except for the-CN group at two different positions. The results show that the open circuit voltage (V-oc = 0.60 V), short circuit density (j(sc) =1.39 mA/cm(2)) and photo-to-electric conversion efficiency (eta = 0.54%) of 5-Aminofluorescein are higher than those of 6-Aminofluorescein (V-oc of 0.58 V, J(sc) of 1.22 mA/cm(2), eta of 0.49), meaning that the 5-Aminofluoresceindisplay a well performance. (C) 2017 Published by Elsevier B.V.