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 ₂:Tm²⁺ (X = Cl, Br, I) by temperature- and time-resolved measurements. At 20K up to four distinct Tm²⁺ emissions can be observed. Most of these emissions undergo quenching via multi-phonon relaxation below 100K. 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.

将 Tm ²⁺掺杂卤化物用于发光太阳能聚光器 (LSC)的前景需要对温度相关的 Tm ²⁺激发态动力学有透彻的了解，该动力学决定了内部量子效率 (QE)，从而决定了 LSC 的效率。在这项研究中，我们通过温度和时间分辨测量研究了 Ca X ₂ :Tm ²⁺ ( X = Cl, Br, I) 中的动力学。在 20K 时多达四个不同的 Tm ²⁺可以观察到排放。这些发射中的大部分通过低于 100K 的多声子弛豫进行淬灭。在更高的温度下，只有最低能量的 5d-4f 发射和 4f-4f 发射仍然存在。将数值速率方程模型拟合到数据表明，随后的 5d-4f 发射猝灭很可能最初是通过多声子弛豫发生的，而在更高的温度下，通过带间交叉产生的额外猝灭被热激活。在室温下，只剩下 4f-4f 发射，相关的 QE 接近 30%。提供了量子效率未达到 100% 的可能原因。