Structural, morphological and optical characterization of CdS-doped silica aerogels synthesized through sol-gel method

Aerogels are highly porous materials characterized by ultra-low density. The incorporation of luminescent materials into silica aerogels results in luminescent aerogels, which have potential applications in light-emitting diodes and optoelectronic devices. In this study, the photoluminescence properties of CdS-doped silica aerogels are reported. The CdS-doped silica aerogels exhibited three distinct emission bands in the blue, green, and red regions. The blue emission is attributed to localized trap states on the CdS surface, while the green emission is associated with sulfur and cation vacancies. The red emission is linked to the substitution of sulfur traps by other counter ions. Supercritical drying of the CdS-doped aerogels resulted in the removal of quantum dots, indicating the non-covalent bonding of CdS nanoparticles to the silica matrix. However, a fraction of the quantum dots remained embedded in the aerogel, as evidenced by weak emission bands and the X-ray diffraction patterns of CdS nanocrystals.