Energy Transfer Efficiency from ZnO-Nanocrystals to Eu3+ Ions Embedded in SiO₂ Film for Emission at 614 nm.

Vivek Mangalam,Kantisara Pita

doi:10.3390/ma10080930

Abstract

In this work, we study the energy transfer mechanism from ZnO nanocrystals (ZnO-nc) to Eu3+ ions by fabricating thin-film samples of ZnO-nc and Eu3+ ions embedded in a SiO2 matrix using the low-cost sol-gel technique. The time-resolved photoluminescence (TRPL) measurements from the samples were analyzed to understand the contribution of energy transfer from the various ZnO-nc emission centers to Eu3+ ions. The decay time obtained from the TRPL measurements was used to calculate the energy transfer efficiencies from the ZnO-nc emission centers, and these results were compared with the energy transfer efficiencies calculated from steady-state photoluminescence emission results. The results in this work show that high transfer efficiencies from the excitonic and Zn defect emission centers is mostly due to the energy transfer from ZnO-nc to Eu3+ ions which results in the radiative emission from the Eu3+ ions at 614 nm, while the energy transfer from the oxygen defect emissions is most probably due to the energy transfer from ZnO-nc to the new defects created due to the incorporation of the Eu3+ ions.

Highlights

The study of the excitation of rare-earth (RE) ions through energy transfers from semiconductor nanocrystals, especially from Zinc oxide nanocrystals (ZnO-nc) has attracted a lot of attention lately.The emission from the 3.37 eV wide bandgap of ZnO-nc has been shown to efficiently excite a wide variety of RE ions ranging from Ce3+ to Yb3+ ions [1,2,3,4,5,6,7,8]
In most of these works, the study of the energy transfer from ZnO-nc is based on steady-state photoluminescence (PL) emission from the nanocrystals, while there have been fewer studies based on time-resolved photoluminescence (TRPL) measurements from the ZnO-nc [2,3]
The weaker interaction of the 360-nm band edge emission (QC) center could be due to the smaller center, and its values depend on the rates of the different de-excitation processes from the ZnO-nc size of the ZnO-nc, as this emission is attributed to the possible quantum confinement effect

Summary

Introduction

The study of the excitation of rare-earth (RE) ions through energy transfers from semiconductor nanocrystals, especially from Zinc oxide nanocrystals (ZnO-nc) has attracted a lot of attention lately. In most of these works, the study of the energy transfer from ZnO-nc is based on steady-state photoluminescence (PL) emission from the nanocrystals, while there have been fewer studies based on time-resolved photoluminescence (TRPL) measurements from the ZnO-nc [2,3]. There have been almost no studies that aim to further the understanding of the de3cay dynamics of various ZnO-nc emission centers and their effect on the efficiency of the energy transfer mechanism from ZnO-nc to RE ions. This article is a direct continuation of our earlier work [9], in which the steady-state PL emission from ZnO-nc was studied to elucidate the contribution of seven ZnO-nc. 22 of emission centers in the energy transfer process to Eu3+ ions. 3+ ions from 3+ radiative centers, mostly duefrom to the the energy transfer from ZnO-nc.

Discussion

Dvacancy

Transfer

Transfer Efficiency from Steady-State Photoluminescence Emission

Materials and Methods