Investigation of bi-colour natural dyes potential for dye sensitized solar cell

Dye is an important element for dye sensitized solar cell (DSC), and acts as an electron receiver when sunlight hits the DSC. It can be obtained from natural colour fruits, vegetables, and parts of plants. Green colour dyes (Chlorophyll pigment) can be extracted from many green leaves such as lettuce leaves, ivy gourd leaves and spinach. purple and red colour dyes (Anthocyanin pigment) can be from roselle and berry. Yellow colour dyes (Carotenoid pigment) can be found in turmeric and pumpkin. In this work, Coccinia grandis (Ivy gourd leaves) is selected to obtain a green colour dye, Oryza sativa Linn (Purple rice) is for purple colour dye and Curcuma longa L. (Turmeric) is for yellow colour dye. The ivy gourd leaves, and turmeric are ground except purple rice and then undergone solvent extraction using 95%-ethanol. The extractions are made with four concentrations of 20, 30, 40 and 50 g of powder per 200 ml of ethanol. The three-colour dyes with different extraction concentrations are investigated for absorbance index to indicate their light absorption abilities. It was found that 30 g/200 ml concentration gave higher light absorption than the 20 g/200 ml concentration, but no significant differences were noticed compared with the 40 and 50 g/200 ml. Thus, the 30 g/200 ml concentration was selected for further investigation. The results showed that the green colour has highest light absorbance following by yellow colour dye and purple colour dye respectively. Then bi-colour dyes mixed between these three dyes were studied. Mixing ratios of primary and secondary colour were also investigated. It was found that green colour dye 80%+ yellow colour dye 20% gave highest light absorption ability compared with the other combinations. It can be noted that bi-colour has wider range of light absorbance compared with a single colour.