Experimental and numerical analysis of Tm2+ excited-states dynamics and luminescence in CaX2 (X = Cl, Br, I)

M. P. Plokker*, I. C. van der Knijff, A. V. de Wit, B. Voet, T. Woudstra, V. Khanin, P. Dorenbos, E. van der Kolk

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

3 Citations (Scopus)
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Abstract

The prospect of using Tm2+-doped halides for luminescence solar concentrators (LSCs) requires a thorough understanding of the temperature dependent Tm2+ excited states dynamics that determines the internal quantum efficiency (QE) and thereby the efficiency of the LSC. In this study we investigated the dynamics in CaX2:Tm2+ (X = Cl, Br, I) by temperature- and time-resolved measurements. At 20 K up to four distinct Tm2+ emissions can be observed. Most of these emissions undergo quenching via multi-phonon relaxation below 100 K. At higher temperatures, only the lowest energy 5d–4f emission and the 4f–4f emission remain. Fitting a numerical rate equation model to the data shows that the subsequent quenching of the 5d–4f emission is likely to occur initially via multi-phonon relaxation, whereas at higher temperatures additional quenching via interband crossing becomes thermally activated. At room temperature only the 4f–4f emission remains and the related QE becomes close to 30%. Possible reasons for the quantum efficiency not reaching 100% are provided.

Original languageEnglish
Article number255701
Number of pages13
JournalJournal of Physics Condensed Matter
Volume33
Issue number25
DOIs
Publication statusPublished - 2021

Keywords

  • CaCl:Tm CaBr:Tm CaI:Tm+
  • Luminescence quenching
  • Photoluminescence
  • Rate equations modelling
  • Tm doped halides
  • Tm excited states dynamics

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