Luminescence Quenching via Deep Defect States: A Recombination Pathway via Oxygen Vacancies in Ce-Doped YAG
Luminescence Quenching via Deep Defect States: A Recombination Pathway via Oxygen Vacancies in Ce-Doped YAG
复制标题
通过深缺陷态发光淬灭：掺 Ce YAG 中通过氧空位的重组途径
作者：
Christopher Linderälv;D. Åberg;P. Erhart
通过非辐射复合通道的发光猝灭限制了荧光粉和闪烁体等光学材料的效率，因此对转换效率和器件寿命有影响。在掺Ce的Y铝石榴石(YAG：Ce)等材料中，猝灭对温度和激活剂浓度都有很强的依赖性，这限制了在较高的工作温度下制作高强度白光发光二极管的能力。在这里，我们通过第一性原理计算揭示了一种涉及氧空位并引起热激活浓度猝灭的有效复合机制。我们证明了这一机制活跃的关键条件是具有很强的电子-声子耦合的局域态。这些条件通常用于宽禁带材料中的本征缺陷，如阴离子空位。因此，本研究结果适用于一大类光学材料，并照亮了一般的热猝灭机制。
Luminescence quenching via non-radiative recombination channels limits the efficiency of optical materials such as phosphors and scintillators and therefore has implications for conversion efficiency and device lifetimes. In materials such as Ce-doped yttrium aluminum garnet (YAG:Ce), quenching shows a strong dependence on both temperature and activator concentration, limiting the ability to fabricate high-intensity white-light emitting diodes with high operating temperatures. Here, we reveal by means of first-principles calculations an efficient recombination mechanism in YAG:Ce that involves oxygen vacancies and gives rise to thermally activated concentration quenching. We demonstrate that the key requirements for this mechanism to be active are localized states with strong electron-phonon coupling. These conditions are commonly found for intrinsic defects such as anion vacancies in wide band-gap materials. The present findings are therefore relevant to a broad class of optical materials and shine light on thermal quenching mechanisms in general.