Characterization of natural dyes as sensitizer for dye-sensitized solar cell

Abstract

In dye-sensitized solar cells (DSSCs) application, sensitizer plays an important part as the molecules from the dye sensitizer which able to converts photons from solar energy into excited electron that can form electrical current after coated with semiconductor of TiO2. Natural dyes from flowers and leaves were chosen as sensitizers replacing the metal complexes dye, Ruthenium, Ru that is widely used in DSSC as the natural dyes are safer, low in cost production and environmentally friendly compared to Ru that resource of metal is limited and high in cost production. This study includes the preparation of natural dyes as sensitizer by using hibiscus sabdariffa (rosella), clitoria ternatea (blue pea flowers) and amaranthus gangeticus (red spinach) that were extracted by using simple method where ethanol was used as solvent to dilute the dyes. This study also involves the determination of characteristics of natural dyes and mixture of the extracts which were identified by observing the pH, FTIR and UV-VIS method and results were compared with the characteristics of synthetic dye of Reactive Black 5 (RB5) with the same method applied. Furthermore, the fabrication of DSSC by using natural and synthetic dyes was done by depositing TiO2 as semiconductor to the FTO conductive glass layer by using doctor’s blade method, hence the photovoltaic results were measured by using multimeter. Red spinach shows the best photovoltaic performance where it produced the highest voltage among the other extracted dyes that the voltage is 313 mV with 0.7 mA of current, however, it is still incomparable with RB5 as sensitizer as RB5 produced voltage at 321 mv with current at 2.10 mA. In overall, most of the extracted natural dyes used in this study shows their potential to absorb solar energy and convert it to electrical energy that improvement is necessary to achieves better performance in future.