Celdas solares sensibilizadas con colorantes fotosensibles obtenidos de plantas de la región sur de Ecuador

Abstract

SENSITIZED SOLAR CELLS WITH PHOTOSENSITIVE DYES OBTAINED FROM PLANTS OF THE SOUTHERN REGION OF ECUADOR.Four vegetal species of the southern of Ecuador were used as sensitizers for making dye-sensitized solar cells (DSSCs). The effect of type and amount of material, type and time of maceration were tested in order to determine the best conditions of extraction. The extraction of the natural dye was made with acidified ethanol. The sensitizing agents were adsorbed on TiO 2 nanoparticles in small solar cells. The DSSCs made with natural dyes from extracts of blackberry (Rubus glaucus B), mortiño (Solanum americanum Mill), escancel (Iresine herbstii Hook) and beet (Beta vulgaris L) developed an open-circuit tension (Voc) 0.65, 0.5, 0.45 and 0.19 V, respectively. The short-circuit currents (Isc) varies from 2.05 to 19.68 mA cm -2 and the fill factor ranging from 0.61 to 0.69. The DSSCs sensitized with the extract of Rubus glaucus B offered the highest maximum power of 8.83 mW. Thus, the natural dyes used showed great potential as sensitizers in DSSCs, besides being environmentally friendly and their low cost.Keywords: Dye-sensitized solar cell; natural dyes; nanoparticles TiO 2 . INTRODUCCIÓNEn el siglo XXI la humanidad se enfrenta al reto del incremento global de la demanda de energía y el control del nivel de emisiones de CO 2 para reducir el efecto invernadero. Por lo cual surge la necesidad en el desarrollo de fuentes de energías alternativas por medio del desarrollo de energías renovables, asegurando protección y armonía con el medio ambiente. 1 Una de estas fuentes de energía alternativa y renovable es el aprovechamiento de la energía solar, mediante la aplicación en celdas solares. Hoy en día, las celdas solares convencionales son basadas en silicio. Sin embargo, su desventaja son los altos costos de fabricación. 2 Otra fuente de energía son los combustibles fósiles, más económicos pero con las desventajas de ser un recurso no renovable y de alta contaminación. 3 Las celdas solares sensibilizadas con colorantes (DSSCs), han despertado un gran interés desde la publicación de O'regan y Grätzel, 4 debido a que representan una alternativa potencial y relativamente económica en comparación con el silicio que son actualmente los más utilizados.Las DSSCs consisten en un electrodo o ánodo, un contra--electrodo o cátodo, electrolito redox (reducción y oxidación) y un agente sensibilizador. 5 En estas celdas, el colorante sensibilizador juega un papel clave en la absorción de la luz solar y la conversión de energía solar en energía eléctrica. Hoy en día, algunos complejos metálicos y colorantes orgánicos se han sintetizado y usado como sensibilizadores. Por el momento, la mayor eficiencia en DSSCs se da por Ru que contienen compuestos absorbidos en TiO 2 nanocristalino alcanzando un 11.1% y una potencia máxima de 2.429 mW. 6 Aunque tales DSSCs han proporcionado un rendimiento relativamente alto, hay varias desventajas de la utilización de metales nobles, debido a su limitada disponibilidad; por lo tanto su producción es...

Impact of solvents on the extraction and purification of vegetable dyes onto the efficiency for dye-sensitized solar cells

“…This indicates that the anthocyanins extracted from each vegetable dye dissolve better in polar aprotic solvent such as ethyl acetate, demonstrating the importance of selecting a suitable solvent for anthocyanin purification. Similar findings have been reported by other researchers, they revealed that polar aprotic solvent such as dimethyl formamide, dimethyl sulfoxide, and acetone managed to extract more anthocyanins from Ixora coccinea flower than those of polar protic solvents such as ethanol and distilled water (Lim et al 2015;Wongcharee et al 2007;Cabrera et al 2017).…”

“…In general, predominance of hydroxyl groups on the aromatic skeleton of anthocyanin gives rise to an intense blue color, while a red color is observed when methoxyl groups prevail instead (Vekariya et al 2016;Nayaran 2012). Anthocyanin compounds have also reported to be found in mora (berries), berenjena (eggplant), rabano (radish), tomate de arbol (tamarillo), ataco (amaranthaceae) and achiote (Wongcharee et al 2007;Polo and Iha 2006;Cabrera et al 2017;Tekerek et al 2011;Chang and Lo 2010). Corresponding natural dyes extracted in ethanol were evaluated as photosensitizers of DSSC, for example, Jaboticaba skin (Myrciaria cauliflora) reported a maximum absorption peak at 538 nm, attributed to peonidin as the principal anthocyanin compound (Polo and Iha 2006); it was also found that the absorption peak of rosella flowers (Hibiscus sabdariffa) extract was about 520 nm, and the anthocyanins obtained from rosella were delphinidin and cyaniding (Calogero et al 2012(Calogero et al , 2015Borras-Linares et al 2015), whereas an absorption peak of blue pea extracts was about 580-620 nm, responsible for its blue color, and the anthocyanin obtained was ternatin (Wongcharee et al 2007).…”

“…Earlier studies have reported that chemical adsorption scheme of anthocyanins onto active adsorption sites on the TiO 2 surface is the result of alcoholic bound protons which condense with hydroxyl groups present at the surface of nanostructured TiO 2 film forms strong complexes showing generally the quinonodial form, which emerges from -OH or =O groups and Ti(IV) sites on the semiconductor nanocrystalline layer (Cherepy et al 1997;Calogero et al 2012). The attachment to the TiO 2 surface stabilizes the exited state and thus shifts toward the lower energy of the absorption maximum (Cabrera et al 2017).…”

“…Accordingly, the structure of the anthocyanins may also affect the performance of DSSC. For example, if the structure has longer R group, this results in the steric hindrance for the anthocyanin to form bond with the oxide surface of the TiO 2 (Calogero et al 2015;Cabrera et al 2017). Hence, it prevents the molecule from chemical adsorption on the TiO 2 film effectively.…”

Performance Simulation of Ipomoea involucrata Dye Extracts for Dye Sensitized Solar Cells

“…Also, the anthocyanin structure can also affect the performance of the devices. It is predicted that a structure with longer R group will result in the hinderance for the anthocyanin to form bond with the oxide in TiO 2 [27,28]. Similarly, difference in dye structure and rate of charge injection into TiO 2 conduction band is responsible for the difference in the current densities [29].…”