Organic semiconductor dyes play a very important role in different criteria and fields of science, technology, and engineering for different applications, especially the absorption of visible light for solar cell devices, photo sensors, fluorescent, photoconductive devices. Basic fuchsine belongs to the triphenylmethane family. It is used on a large scale as a coloring agent for the staining of biological tissues, leather, and textile materials. The Z-scan technique is based on the principles of spatial distortion of the beam and offers simplicity, as well as a very high sensitivity for measuring both the nonlinear refractive index as well as the non-linear absorption coefficient. For the present work we propose the study of 6 star-type dyes derived from basic fushcine with azo groups added, by the Z-scan technique. A 1 × 10<sup>-4</sup> M dilution of each dye in methanol was prepared. Subsequently, the linear characterization was made with the help of the UV-vis technique and finally, the analysis was carried out in the Z-scan equipment. The dyes have a λmax between 500-570 nm, and with n<sub>2</sub> = -1.7 × 10<sup>-9</sup> to 6.63 × 10<sup>-9</sup> and β = 1.1 × 10<sup>-3</sup> to 6.3 × 10<sup>-4</sup>. These results allow us to propose these dyes as good options for their incorporation into solar cells as well as optical absorbers.
By incorporating low weight percentages of graphene in our precursor solution and using a technique derived from spray pyrolysis, we obtained a low cost TCO with excellent properties, characterized by AFM, UV-VIS and Hall Effect. The film roughness was calculated to be ~7.49-12.7 nm, while band gap was determined to be ~4.0-4.2 eV. The material’s optical transparency ranges from 84-86% and its resistivity was measured to be ~5.5-8.5 x10<sup>-3</sup> Ω cm. With these results, we suggest that the obtained material is a proper candidate for use in photovoltaic applications, such as Grätzel solar cells, which will be our main focus.