SiO2-TiO2 doped with Er3+/Yb3+/Eu3+ photoluminescent material: A spectroscopy and structural study about potential application for improvement of the efficiency on solar cells

Highlights: • Intense downconversion emission of Eu³⁺ under Uv excitation. • Upconversion emission assigned to the Er³⁺/Yb³⁺ under 980 laser pump. • Double excitation simultaneous providing emission in visible range. • Potential application on improvement of solar cells. - Abstract: The various synthesis conditions to obtain a material based on SiO₂-TiO₂ co-doped with Er³⁺/Yb³⁺/Eu³⁺ were investigated, searching for those that present the greatest potential to improve the efficiency of solar cells. Conditions adjusted included heat-treatment temperatures, concentrations of matrix, and concentrations of dopants. Raman spectroscopy results demonstrated the effect of the annealing temperatures on the TiO₂ phase transition and the crystalline phase of the materials, which interfere with the photoluminescence of the materials. The band gap of the materials was evaluated by diffuse reflectance and it decreased due to the doping. The materials were able to absorb UV and IR energy and emit in the visible region, verified by the down conversion, up conversion and the double excitation of the materials. The results showed that the materials may be used as a strategy to use a greater portion of the solar spectrum, improving solar cell efficiency.