ABSTRACT

ZnO/natural dyes solar cell (DSSC) had been successfully synthesised. The preparation of ZnO thin films was carried out on an indium thin oxide (ITO) glass substrate using the sol-gel spin coating method. The natural dyes were extracted from tamarillo, red dragon fruit, red spinach, boat lily flower and purple hibiscus flower, each cut into small pieces and put into a beaker glass. The sample was then further crushed with a mortar and then milled until it became soft. The extracted dyes were heated for 5 h and diluted with distilled water to obtain dye solutions. The DSSC structure was formed by glueing together the ZnO/dye and a platinum plat by using Surlyn. The ZnO/dye and platinum were successively used as a working electrode and counter electrode. The Surlyn functioned as glue and conductor. The DSSC structure then put on a hot plate with a temperature of 70°C–80°C to enable Surlyn pasted perfectly. Further, electrolyte liquid was injected into the ZnO/dye-platinum structure. The ZnO thin films were characterised by X-ray powder diffraction (XRD), scanning electron microscope (SEM) and UV-Vis spectrometer. The ZnO/natural dyes thin films were formed by dipping the ZnO thin film into natural dyes solution with the ZnO thin films facing up for 24 h to let the dyes adsorbed by the film. DSSC efficiencies were measured by a simple circuit consisting of DSSC, both analogue and digital multimeters. The results showed that the ZnO crystal structure was of wurtzite hexagonal shape with a crystallite size of 27.3 nm, high-density granules with narrow inter granules boundary, and the band-gap was 3.25 eV. The maximum and minimum values of the sensitisers were from red spinach and red dragon fruit which were 3.30 a.u and 2.50 a.u. The DSSC can convert solar energy to electrical energy with power and efficiency of consecutively of 0.101 W cm^–2 and 0.278%.

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