Bae Hyeongyu, Park Dongcheol, Shin Kyujin, Lee Hohjai, Ok Kang Min, Lee Kang Taek
Department of Chemistry, Gwangju Institute of Science and Technology, Cheomdangwagi-ro 123, Buk-gu, Gwangju, Republic of Korea.
Department of Chemistry, Sogang University, Seoul 04107, Republic of Korea.
J Chem Phys. 2021 Feb 7;154(5):054701. doi: 10.1063/5.0024941.
Despite advances of lanthanide-doped upconversion (UC) materials, the applications such as light-emitting diode and biological imaging are limited by low quantum efficiency. For this context, the understanding of unique interactions between the doped-lanthanides and the host crystals has attracted a huge amount of the researcher's interest. In particular, it was revealed that doping lanthanide ions in a non-centrosymmetric site of host lattice is the cause of relaxation of the Laporte selection rule in the 4f-4f transition of lanthanide ions. One of the layered perovskites CsBiNbO is known to have non-centrosymmetric sites, which would lead to highly bright UC emission. Nevertheless, to our knowledge, there has been no research on the UC comparison between host materials of CsBiNbO with other hosts. In this article, we present the UC intensity comparison of Yb-Er ion doped CsBiNbO, NaYF, BaTiO, and SrTiO hosts (the UC in CsBiNbO:Er,Yb was 2.4 times that of NaYF:Er,Yb and ∼70 times that of SrTiO:Er,Yb). After that, we dig into UC, downshifting, and double beam system UC properties. The activator concentration was optimized by varying the doping ratio of Yb and Er, and we found out the main reason for the concentration quenching behavior in Er ion doped CsBiNbO is dipole-dipole interaction. In addition, the double excitation experiment indicates that the absorption (I → I) factor is stronger than the stimulated emission (I → I) factor in CsBiNbO under 1540 nm laser irradiation.
尽管镧系元素掺杂的上转换（UC）材料取得了进展，但发光二极管和生物成像等应用仍受到低量子效率的限制。在此背景下，对掺杂镧系元素与主体晶体之间独特相互作用的理解引起了研究人员的极大兴趣。特别是，研究发现，在主体晶格的非中心对称位置掺杂镧系离子是导致镧系离子4f-4f跃迁中拉波特选择规则弛豫的原因。层状钙钛矿之一的CsBiNbO已知具有非中心对称位置，这将导致高亮度的上转换发射。然而，据我们所知，尚未有关于CsBiNbO主体材料与其他主体材料之间上转换比较的研究。在本文中，我们展示了Yb-Er离子掺杂的CsBiNbO、NaYF、BaTiO和SrTiO主体的上转换强度比较（CsBiNbO:Er,Yb中的上转换强度是NaYF:Er,Yb的2.4倍，约为SrTiO:Er,Yb的70倍）。之后，我们深入研究了上转换、下转换和双光束系统的上转换特性。通过改变Yb和Er的掺杂比例优化了激活剂浓度，我们发现Er离子掺杂的CsBiNbO中浓度猝灭行为的主要原因是偶极-偶极相互作用。此外，双激发实验表明，在1540 nm激光照射下，CsBiNbO中的吸收（I→I）因子强于受激发射（I→I）因子。
