Fabrication of Dye Sensitized Solar Cell and Efficiency Enhancement by Using N719 and Z907 Dyes Mixture

Abstract

This study aims to investigate the effect of N719 and Z907 dyes mixture (1:1 v/v ratio) on the DSSCs fabricated successfully using a simple procedure without the need for any complicated facilities. The XRD analysis of the TiO2 layer confirmed that it has a polycrystalline structure belonging to anatase phase with crystallite size of 12.4 nm. UV-Vis spectroscopy was used to characterize the absorbance spectra of the TiO2 layer, N719 dye, Z907 dye, dyes mixture and the fabricated DSSCs as well. The absorption spectra in the wavelength range of (350-750) nm show that the DSSC fabricated with dyes mixture has higher absorption compared to the other two cells. The dyes mixture performs better than the individual dyes due to the broadening of its UV-Vis spectrum in the blue region. The energy gap of the TiO2 layer estimated by Tauc’s plot was 3.12 eV. The SEM micrograph of the TiO2 layer shows that the layer has a spongy shape with reduction in the number of open pores making easy for dye adsorption and electron transport. The average roughness, root mean square roughness and grain size of the TiO2 layer estimated from the AFM micrograph and the granularity cumulative distribution chart were about 0.356 nm, 0.423 nm and 82.48 nm respectively. Solar cells with efficiency as high as 2.287% have been achieved using the dyes mixture as sensitizer which represents an enhancement of ~ 70% and ~ 106% compared to the DSSCs efficiencies prepared by N719 and Z907 dyes respectively.