Improvement efficiency of a dye-sensitized solar cell using Eu³⁺ modified TiO₂ nanoparticles as a secondary layer electrode

This novel work presents the successful size control of Eu ³⁺_x-modified TiO₂ nanoparticles by adding various amounts of Eu³⁺. The electronic structures of Eu ³⁺_x-modified TiO₂ nanoparticles are different from those of pure TiO₂ nanoparticles, as analyzed by DRS (UV-Vis diffuse reflectance spectroscopy) and XPS (X-ray photoelectron spectroscopy). As Eu³⁺_x-modified TiO₂ nanoparticles are used as a second layer in the double-layered electrode, the probability of recombination of excited electrons and holes is reduced to increase the short-circuit current (J_SC) during the operation of the dye-sensitized solar cells (DSSCs). The increase in the open circuit voltage (V_oc) from 0.66 to 0.71 V is observed owing to the energy of the conduction band in Eu ³⁺_x-modified TiO₂ layer. Finally, the efficiency (η) is clearly improved from 2.20 to 3.43% when the double-layered structure of Eu_0.03-TiO₂/Eu ₀-TiO₂ is adopted in the DSSCs.