Wydział Chemii

Eugeniusz Zych

Joanna Trojan-Piegza

2006

Chemistry of Materials

18

2194-2199

10.1021/cm052774q

Naukowa

Angielski

Artykuł

Synchrotron radiation has been used to characterize the low-temperature (10 K) spectroscopic properties of Lu₂O₃:Eu phosphors containing varying amount of the dopant. Upon excitation at energies in the vicinity of the band gap, the nominally undoped specimen produced three different emissions. The highest energy luminescence, located at 260 nm, was attributed to direct recombination of electrons and holes. We also found a broad band emission at 380 nm, which we attribute to self-trapped excitons (STEs) on the basis of the excitation spectra of the various emissions. Finally, in doped specimens, we also recorded emission produced by the Eu³⁺ activator. We found that the e−h recombination luminescence at 260 nm was severely quenched in the presence of Eu, disappearing completely at a concentration of 0.1 atom %. The 380 nm STE luminescence intensity decreased much more slowly with increasing Eu content, until at 5 atom % it too disappeared, leaving only the Eu³⁺ emission. This emission became gradually more and more intense with increasing activator content. We found that while excitons carry more than enough excitation energy, they prefer to annihilate radiatively without passing their energy to Eu³⁺ ions. Hence, we concluded that the only efficient channel of energy transfer from the excited host to the activator is through sequential trapping and subsequent recombination of free electrons and holes.

Electrical energy, Luminescence, Energy, Recombination, ions

https://doi.org/10.1021/cm052774q

https://www.acs.org/content/acs/en.html