Comparative Study on the Optical Properties and Quantum Efficiency of Congo Red Dye Doped with SiO₂, MgO, and TiO₂ Nanoparticle

This study focused on improving the optical properties of the Congo Red pigment using different nanoparticles (SiO2, MgO, and TiO2) at different weight concentrations (0.002, 0.004, and 0.006 g). The results showed that the addition of nanoparticles led to a significant improvement in absorbance (A), refractive index (n), and dielectric constant, while the transmittance (T) decreased. Regarding absorbance at the highest concentration (0.006 g): the pure dye recorded an absorbance of 0.204, while it increased to 0.325 with the addition of SiO₂, to 0.361 with MgO, and reached its maximum value of 0.626 with TiO₂. Conversely, the transmittance (T) decreased at the same concentration: from 0.623 for the pure dye, to 0.473 with SiO₂, 0.435 with MgO, and recorded its lowest value of 0.236 with TiO₂, indicating the high light-blocking efficiency of titanium dioxide. Fluorescence results also showed that the quantum efficiency (QE) decreased with Increasing the concentration for all samples, the highest quantitative efficiency was recorded at the lowest concentration (0.002 g) and the values were as follows: 0.0459 with SiO2, 0.04 with MgO, and the highest 0.0475 with TiO2.