Zhou Weiying, Fan Jiaqi, Luo Jiabao, Lin Lemin, Zhou Jiaxin, Zhang Jilin, Zhu Zhenpeng, Zhang Xinguo
NMPA Key Laboratory for Research and Evaluation of Drug Metabolism, Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China.
Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China), College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 10081, China.
Inorg Chem. 2022 Jun 13;61(23):8767-8781. doi: 10.1021/acs.inorgchem.2c00712. Epub 2022 May 27.
Despite an encouraging progress, Mn-activated red phosphors suffer from an insufficient emission intensity and a bad color purity. Thus, it is necessary to find a new strategy to realize a bright red emission through highly efficient Mn sensitization. Herein, manipulating Eu-sensitized SrLiMn(PO) (SLMP) composition by Ln heterovalent substitution is proved to be able to substantially gain a tremendous Mn emission enhancement and result in a dominant red Mn emission. It is found that the emission enhancement ratio is proportional to the order of lanthanide contraction. Notably, Tb doping realizes a 427-fold rise in the integrated emission intensity compared with the SLMP host, which is close to the theoretical maximum of 500. An underlying mechanism for Mn red emission enhancement is proposed, which is attributed to a high-energy transfer probability from Eu to Mn Ln-induced further structural confinement plus an energetic match effect. Meanwhile, homovalent (Ca) substitution could precisely tailor Mn emitting color from orange-red to deep red. A warm-white LED device with a low color temperature of 3394 K, a high color-rendering index of 90.2, and suitable CIE coordinates of (0.403, 0.373) is fabricated using optimized phosphor SLMP:Eu, Tb. These results might reveal a new strategy to develop new red-emitting phosphors with a bright and highly purified red Mn emission.
尽管取得了令人鼓舞的进展，但锰激活的红色荧光粉仍存在发射强度不足和色纯度差的问题。因此，有必要找到一种新策略，通过高效的锰敏化来实现明亮的红色发射。在此，通过镧系元素异价取代来调控铕敏化的SrLiMn(PO)（SLMP）组成，被证明能够大幅提高锰的发射强度，并产生占主导地位的红色锰发射。研究发现，发射增强率与镧系收缩顺序成正比。值得注意的是，与SLMP基质相比，铽掺杂使积分发射强度提高了427倍，接近理论最大值500。提出了一种锰红色发射增强的潜在机制，这归因于从铕到锰的高能量转移概率、镧系元素诱导的进一步结构限制以及能量匹配效应。同时，同价（钙）取代可以精确地将锰的发射颜色从橙红色调整为深红色。使用优化后的荧光粉SLMP:Eu,Tb制备了一个色温低至3394 K、显色指数高达90.2且CIE坐标合适（0.403,0.373）的暖白色发光二极管器件。这些结果可能揭示了一种开发具有明亮且高度纯化的红色锰发射的新型红色发光荧光粉的新策略。
