Annealing effect on the structural and optical behavior of ZnO:Eu3+ thin film grown using RF magnetron sputtering technique and application to dye sensitized solar cells

Francis Otieno; Mildred Airo; Rudolph M Erasmus; Alexander Quandt; David G Billing; Daniel Wamwangi

doi:10.1038/s41598-020-65231-6

Annealing effect on the structural and optical behavior of ZnO:Eu³⁺ thin film grown using RF magnetron sputtering technique and application to dye sensitized solar cells

Sci Rep. 2020 May 22;10(1):8557. doi: 10.1038/s41598-020-65231-6.

Authors

Francis Otieno^{1

2}, Mildred Airo³, Rudolph M Erasmus⁴, Alexander Quandt⁴, David G Billing³, Daniel Wamwangi^{3

4}

Affiliations

¹ Molecular Science Institute, School of Chemistry, University of the Witwatersrand, Private Bag 3, Wits, 2050, Johannesburg, South Africa. frankotienoo@gmail.com.
² Material Physics Research Institute (MPRI), School of Physics, University of the Witwatersrand, Private Bag 3, Wits, 2050, Johannesburg, South Africa. frankotienoo@gmail.com.
³ Molecular Science Institute, School of Chemistry, University of the Witwatersrand, Private Bag 3, Wits, 2050, Johannesburg, South Africa.
⁴ Material Physics Research Institute (MPRI), School of Physics, University of the Witwatersrand, Private Bag 3, Wits, 2050, Johannesburg, South Africa.

Abstract

Eu-doped ZnO (ZnO:Eu³⁺) 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 Eu³⁺ ions as enhanced by the intrinsic defects levels. Five peaks corresponding to ⁵D0-7F_J transitions were observed and attributed to Eu³⁺ occupancy in the lattice sites of ZnO thin films. As a proof of concept a dye sensitized solar cell with ZnO:Eu³⁺ 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:Eu³⁺.