Engineering and Technology Journal

In this research, AuNPs prepared by laser ablation in liquid (PLAL) at 750 mJ energy and 90 pulses. They have been added to N719-dye to form (Au-N719) mixture. TiO2 paste was deposited on FTO substrates and immersion in a mixture dye and AuNPs. DSSC was fabricated and enhancement of the DSSC conversion efficiency was achieved. Scanning electron microscope, X-ray diffraction and UV-Visible spectrophotometer were used to characterize and study the DSSC components. The UV-Vis data show high absorbance of AuNPs+N719 dye compared to N719 dye only; that means the immersion of AuNPs in the N719-dye solution tend to increase the total absorbance of the dye. The XRD pattern of AuNPs has diffraction peaks at 38.2° and 44.4° which can be indexed by (111), (200) plane of Au in the cubic phase. The shape and size distribution shows spherical AuNPs with particle size about (50-60) nm. The relative increase of short circuit current density after the adding gold nanoparticles was about 76%. In the same way the relative increase of open circuit voltage after adding gold nanoparticles was about 6.7%. The total photon-to-current energy conversion efficiency for the standard DSSC is 1.75 while its 2.8 of the enhanced DSSC with gold NPs.The maximum enhancement is about 60 % under illumination (105 mW/cm2, (AM1.5).

In this work, the spectral properties of the Hibiscus sabdariffa organic dye solved in different solvents were studied by introducing the effect of dye concentration on its absorbance and transmission spectra within the range 400-800nm. As well, the effect of adding impurity particles of a semiconductor to the dye solution on these properties was introduced. Results showed that the spectral properties of the dye depend substantially on the type of the solvent, which has to be chosen carefully to achieve the optimum properties of this dye to be used as a sunlight sensing organic medium in dye-sensitized solar cells. Also, the results showed that the spectral properties of this dye are noticeably affected by the presence of impurity particles of a semiconductor when the suitable solvent is used. These particles act as scattering centers through the solution to the electromagnetic radiation in the visible region and hence the intensities of the absorbed and transmitted components of the radiation are decreased