Lanthanide Sensitization in II–VI Semiconductor Materials: A Case Study with Terbium (III) and Europium (III) in Zinc Sulfide Nanoparticles

摘要

This work explores the sensitization of luminescent lanthanide Tb³⁺ and Eu³⁺ cations by the electronic structure of zinc sulfide (ZnS) semiconductor nanoparticles. Excitation spectra collected, while monitoring the lanthanide emission bands, reveals that the ZnS nanoparticles act as an antenna for the sensitization of Tb³⁺ and Eu³⁺. The mechanism of lanthanide ion luminescence sensitization is rationalized in terms of an energy and charge transfer between trap sites and is based on a semi-empirical model, proposed by Dorenbos and coworkers, ^– to describe the energy level scheme. This model implies that the mechanisms of luminescence sensitization of Tb³⁺ and Eu³⁺ in ZnS nanoparticles are different; namely Tb³⁺ acts as a hole trap, while Eu³⁺ acts as an electron trap. Further testing of this model is made by extending the studies from ZnS nanoparticles to other II–VI semiconductor materials; namely, CdSe, CdS, and ZnSe.