Lanthanide networks in luminescent materials: insights from Monte-Carlo simulations

Groep: LumiLab

Promotor: dr. Jonas Joos, prof. dr. Philippe Smet

Supervision: dr. Jonas Joos

Luminescent materials, also known as phosphors, have very interesting properties for a variety of applications. They are typically composed of an inorganic crystal, which is doped by luminescence activators, often lanthanide (4f series) ions. Traditional application domains are medical imaging and LED-based lighting. To date, many questions remain on the precise physical processes responsible for their particular luminescent behavior, and a combination of theory and experiment is often needed to gain a deeper understanding.

Here, processes related to the interaction within networks of lanthanide ions inside the crystalline matrix are studied by means of Monte-Carlo simulations. Two distinct mechanisms exist for lanthanide ions to interact. Firstly, they can resonantly transfer energy which can give rise phenomena such as quantum cutting where a UV photon is converted in two infrared photons (see Figure), or upconversion, the opposite effect. However exotic, these phenomena have been proposed to improve the efficiency of solar cells or concentrators, potentially having a significant societal impact. Secondly, charge carriers can be exchanged between lanthanide ions. Such electron transfers can induce energy storage which lies at the origin of afterglow phosphors, or medical imaging plates depending on the details of the interaction. Although the basics of these phenomena are roughly understood, important knowledge gaps remain. These pertain mainly to the type and range of the interactions. As a consequence, materials are usually developed and optimized in a trial-and-error fashion.

In this thesis, these knowledge gaps are considered via kinetic Monte-Carlo (MC) simulations, using effective expressions for the atomic-scale interactions in order to investigate what kind of phenomena emerge on a macroscopic scale. Although this project is predominantly theoretical, experimental facilities are readily available that allow to confront theoretical results with experiment, thus increasing the impact of new findings.

Lanthanide networks in luminescent materials

Opmerkingen:

  • Dit thesisonderwerp kan ook opgenomen worden in het kader van de Educatieve Master Fysica en Sterrenkunde.
  • Aan dit onderwerp is geen mobiliteitsaspect verbonden. Er kan met de promotoren wel overlegd worden over gerelateerde stage-activiteiten en/of vakken aan andere universiteiten.