Evaluating the Tm2+ 4f125d1 → 4f13 and 4f13 → 4f13 Luminescence and Quenching Dynamics in Orthorhombic BaCl2

The luminescence properties of Tm2+-doped BaCl2 with an orthorhombic structure have been studied as a function of temperature and compared to other Tm2+-doped chlorides. In addition to the 2F5/2 → 2F7/2 (4f13 → 4f13) line emission, two 4f125d1 → 4f13 band emissions are observed at 20 K that can be ascribed to the spin-allowed (3H6,5d1)S=1/2 →...

Unfolding the Excited States Dynamics of Tm²⁺-doped Halides: In Prospect of Novel Luminescence Solar Concentrators

Tm²⁺-doped halides exhibit excellent properties for use in Luminescence Solar Concentrator (LSC) applications. Such LSCs consist of a glass waveguide with small Copper-Indium- Selenide (CIS) solar cells attached to its edges. The waveguide contains a luminescent coating based on a Tm²⁺-doped halide, whose 4f125d1 absorption...

The potential of transparent sputtered NaI:Tm²⁺, CaBr₂:Tm²⁺, and CaI₂:Tm²⁺ thin films as luminescent solar concentrators

The parameters governing the performance of a luminescent solar concentrator (LSC) are determined for sputtered thin-films of NaI:Tm²⁺, CaBr₂:Tm²⁺, and CaI₂:Tm²⁺. These parameters are determined by using six gradient thin film material libraries, combinatorially sputtered from metallic...

Photoluminescence and excited states dynamics of Tm²⁺-doped CsCa(Cl/Br)₃ and CsCa(Br/I)₃ perovskites

In this study, we systematically vary the Cl/Br and Br/I ratios in CsCaX₃:Tm²⁺ (X = Cl, Br, I) and hereby gradually shift the positions of the Tm²⁺ 4f¹²5d¹-levels as relative to the two 4f¹³ levels. At low temperatures up to five distinct Tm²⁺ 4f¹²5d<sup>1...

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

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 CaX<sub...

Concentration and temperature dependent luminescence properties of the SrI₂-TmI₂ system

The concentration dependent luminescence of the SrI₂-TmI₂ system was investigated. For Tm²⁺ concentrations up to 5 mol %, the quantum efficiency (QE) of the ²F_5/2→²F_7/2 emission exhibits a constant value above 50%. The QE drops for higher Tm²⁺...

Temperature dependent relaxation dynamics of luminescent NaX:Tm²⁺ (X=Cl, Br, I)

In recent years, Thulium in its 2 + oxidation state has been identified as candidate dopant in halide hosts for luminescent solar concentrators. Yet, some of its luminescent properties with regard to these applications remain unexplored. In this study we report on the temperature dependent photo-luminescent behaviour of NaCl:Tm²⁺,...

Electronic structure and vacancy formation in photochromic yttrium oxy-hydride thin films studied by positron annihilation

In order to investigate the mechanism of the photochromic effect in yttrium oxy-hydride (YO_xH_y) thin films, Doppler broadening positron annihilation spectroscopy (PAS) was applied to probe the electronic structure and the presence of vacancies in YO_xH_y and related materials as a function of...

Structural and electrical properties of metastable defects in hydrogenated amorphous silicon

The structural and electrical properties of metastable defects in various types of hydrogenated amorphous silicon have been studied using a powerful combination of continuous wave electron-paramagnetic resonance spectroscopy, electron spin echo (ESE) decay measurements, and Doppler broadening positron annihilation spectroscopy. The observed...