A combined spectroscopic and TDDFT study of natural dyes extracted from fruit peels of Citrus reticulata and Musa acuminata for dye-sensitized solar cells

This study reports the novel spectroscopic investigations and enhanced the electron transfers of Citrus reticulate and Musa acuminate fruit peels as the photosensitizers for the dye-sensitized solar cells. The calculated TD-DFT-UB3LYP/6-31 + G(d,p)-IEFPCM(UAKS), experiment spectra of ultra-violet visible spectroscopy, and Fourier transform infrared spectroscopy studies indicate the main flavonoid (hesperidin. and gallocatechin) structures of the dye extracts. The optimized flavonoid structures are calculated using Density functional theory (DFT) at 6-31 + G(d,p) level. The rutinosyl group of the hesperidin pigment (Citrus reticulate) will be further investigated compared to the gallocatechin (Musa acuminate) pigment. The acidity of the dye extract is treated by adding 2% acetic acid. The energy levels of the HOMO-LUMO dyes are measured by a combined Tauc plot and cyclic voltammetry contrasted with the DFT data. The electrochemical impedance spectroscopy will be performed to model the dye electron transfer. As for the rutinosyl group presence and the acidic treatment, the acidified Citrus reticulate cell under continuous light exposure of 100 mW.cm(-2) yields a short-circuit current density (J(sc)) of 3.23 mA/cm(2), a photovoltage (V-oc) of 0.48 V, and a fill factor of 0.45 corresponding to an energy conversion efficiency (77) of 0.71% because the shifting down HOMO-LUMO edges and the broadening dye's absorbance evaluated by a combined spectroscopic and TD-DFT method. The result also leads to the longest diffusion length of 32.2 mu m, the fastest electron transit of 0.22 ms, and the longest electron lifetime of 4.29 ms. (C) 2016 Elsevier B.V. All rights reserved.