Annealing effect on the structural and optical behavior of ZnO:Eu(3+) thin film grown using RF magnetron sputtering technique and application to dye sensitized solar cells

Eu-doped ZnO (ZnO:Eu(3+)) thin films deposited by RF magnetron sputtering have been investigated to establish the effect of annealing on the red photoluminescence. PL spectra analysis reveal a correlation between the characteristics of the red photoluminescence and the annealing temperature, suggesting efficient energy transfer from the ZnO host to the Eu(3+) ions as enhanced by the intrinsic defects levels. Five peaks corresponding to (5)D0–7F(J) transitions were observed and attributed to Eu(3+) occupancy in the lattice sites of ZnO thin films. As a proof of concept a dye sensitized solar cell with ZnO:Eu(3+) thin films of high optical transparency was fabricated and tested yielding a PCE of 1.33% compared to 1.19% obtained from dye sensitized solar cells (DSSC) with pristine ZnO without Eu produced indicating 11.1% efficiency enhancement which could be attributed to spectral conversion by the ZnO:Eu(3+).