Photoactive Layer of DSSCS Based on Natural Dyes: A Study of Experiment and Theory

Three natural dyes (Forsythia suspensa, Herba Violae, and Corn leaf) have been investigated as potential sensitizers for dyesensitized solar cells. UV-vis absorption spectra reveal that three natural dyes mainly contain the compound of pheophytin a. Among three DSSCs, the highest photo electronic conversion efficiency eta is 0.96% with open circuit voltage (V-OC) of 0.66V, short circuit current density (I-SC) of 1.97 mA cm(-2), and fill factor (ff) of 0.74. Theoretical time-dependent density functional theory and charge difference density are used to explore the nature of excited states. Results demonstrate that the first state is an intramolecular charge transfer (ICT) state, and electron injection could occur owing to the thermodynamically driving force.