Exploring Intrinsic Electron-Trapping Centers for Persistent Luminescence in Bi3+-Doped LiREGeO4 (RE = Y, Sc, Lu): Mechanistic Origin from First-Principles Calculations.
Exploring Intrinsic Electron-Trapping Centers for Persistent Luminescence in Bi3+-Doped LiREGeO4 (RE = Y, Sc, Lu): Mechanistic Origin from First-Principles Calculations.
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DOI：
10.1021/acs.inorgchem.1c02507
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发表时间：
2021-10
影响因子：
4.6
通讯作者：
Zheng Qiao;Xuesong Wang;Chen Heng;W. Jin;Lixin Ning
中科院分区：
文献类型：
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作者：
Zheng Qiao;Xuesong Wang;Chen Heng;W. Jin;Lixin Ning
从实验的角度来看，揭示无机磷光体中作为电荷载流子捕获中心的持久发光（EFL）的本征缺陷的性质仍然是一个至关重要的挑战。最近有报道称，Bi 3+掺杂的LiREGeO 4（RE = Sc、Y、Lu）化合物在室温下在~ 360 nm处显示出强的紫外A PersL，持续时间为数十小时。然而，这一机制的起源仍然有待揭开。在这里，我们进行了系统的研究，光学跃迁，形成能量，和电荷跃迁的掺杂剂和本征点缺陷在这些化合物中使用混合密度泛函理论计算。结果表明，在254 nm处的有效充电是由于Bi 3+的D带跃迁，因此与Bi 3L有关的电荷载流子是来自掺杂剂的电子，这些电子参与了俘获和释放过程。主要的电子俘获中心是反位缺陷GeLi 0、间隙缺陷Li 1 0和掺杂剂Bi 2+，前者是强反位缺陷的原因，后者是长时间反位缺陷的原因.通过与NaLuGeO 4和LiLuSiO 4的计算结果的比较，进一步证实了这些发现，并阐明了Li和Ge元素在形成具有适当陷阱深度的本征缺陷中的作用。我们的研究结果不仅有助于理解实验观察，而且还提供了一个理论基础，为合理设计的新的含锂和锗的基质化合物的荧光粉。
Revealing the nature of intrinsic defects that act as charge-carrier trapping centers for persistent luminescence (PersL) in inorganic phosphors remains a crucial challenge from an experimental perspective. It was recently reported that Bi3+-doped LiREGeO4 (RE = Sc, Y, Lu) compounds displayed strong ultraviolet-A PersL at ∼360 nm with a duration of tens of hours at room temperature. However, the mechanistic origin of the PersL remains to be unveiled. Herein, we carried out a systematic study on optical transitions, formation energies, and charge-transition levels of dopants and intrinsic point defects in these compounds using hybrid density functional theory calculations. The results show that the efficient charging by 254 nm is due to the D-band transition of Bi3+ and hence the charge carriers pertinent to PersL are electrons originating from the dopants which are involved in the trapping and detrapping processes. The main electron-trapping centers are antisite defects GeLi0, interstitial defects Lii0, and dopants Bi2+, with the former one responsible for the strong PersL and the latter two for its long-time duration. These findings are further confirmed by comparison with calculated results for isostructural NaLuGeO4 and LiLuSiO4, based on which the roles of Li and Ge elements in forming intrinsic defects with appropriate trap depths for PersL are clarified. Our results not only assist in the understanding of experimental observations but also provide a theoretical basis for the rational design of novel PersL phosphors containing lithium and germanium in the host compound.