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 Eu3+x-modified TiO2 nanoparticles by adding various amounts of Eu3+. The electronic structures of Eu3+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 (JSC) during the operation of the dye-sensitized solar cells (DSSCs). The increase in the open circuit voltage (Voc) from 0.66 to 0.71 V is observed owing to the energy of the conduction band in Eu3+x-modified TiO2 layer. Finally, the efficiency (η) is clearly improved from 2.20 to 3.43% when the double-layered structure of Eu0.03-TiO2/Eu0-TiO2 is adopted in the DSSCs.