Anthocyanins from Ceibo flower as natural dye for its use in DSSC

PAULA ENCISO; MARÍA FERNANDA CERDÁ; FRANCO M. CABRERIZO

Córdoba

Congreso; 16th International Congress of Photobiology; 2014

Dye sensitized solar cells (DSSC) are photoelectrochemical devices that resemble natural photosynthesis, because they use an organic dye to absorb light and produce a flow of electrons [1]. Today, many researches are conducting around the search of the best dye in order to improve energy efficiency conversion [2]. The use of natural dyes is an attractive alternative due to the low cost of fabrication and the environmental benefits related to their employment [3-4]. In this work we characterize the anthocyanins from the Ceibo flower. We carried out spectroscopic, voltammetry and thermal stability studies in order to evaluate the potential use of such dyes as sensitizer for DSSC. UV-visible spectrum of anthocyanins in ethanolic solution showed a maximum centered at 530 nm. From spectroscopic data a value of 2.23 eV for the energy difference between the vibrationally relaxed levels of the first electronic excited state, S1, and the ground state, S0, of the dye (E0,0) was calculated. The dyes also showed suitable redox potentials, i.e., 1.3 V vs. Ag/AgCl. Taking into account these results, in connection with the redox potential of the anatase-TiO2 conduction band (-0.53 V) and I-/I3- electrolyte (0.35 V), a spontaneous electron transfer reaction can be predicted. Additionally, the sensitizer showed good stability in the presence of quite high concentration of the electrolyte and also some solvents commonly used in this type of cells. [1]  B. O´Regan, M. Grätzel, Nature, 1991, 353, pp. 737-740. [2] M. Narayan, Renewable and Sustainable Energy Reviews, 2012, 16, pp. 208-215. [3] G. Calogero, J.H. Yun, A. Sinopoli, G. Marco; M. Grätzel, M. Nazeeruddin, Solar Energy, 2012, 86, pp. 1563-1575. [4] P. Enciso; F.M. Cabrerizo, J. Gancheff, P. Denis, M.F. Cerdá, J. Applied Solution Chemistry and Modeling, 2013, 2, pp. 225-233.