A novel red-emitting NaYS2 upconversion phosphor under 1550 nm excitation

• Published in: Hanʼguk Seramik Hakhoe chi Vol. 61; no. 5; pp. 890 - 895
• Main Authors: Wu, Jiulong, Tian, Ying, Li, Jiayao, Wei, Limin, Cai, Ke, Luo, Xixian, Wang, Hong
• Format: Journal Article
• Language: English
• Published: Singapore Springer Nature Singapore 01.09.2024
• Subjects: Ceramics; Chemistry and Materials Science; Composites; Glass; Materials Science; Natural Materials; Original Article; NaYS; 1550 nm; Energy transfer; Red upconversion luminescence
• ISSN: 1229-7801; 2234-0491
• DOI: 10.1007/s43207-024-00402-z

Up-conversion luminescence (UCL) materials are of great importance due to their unique optical properties. In particular, the red UCL, falling into the optical transmittance window of biological tissues, can realize deep tissue penetration depth and high-resolution bioimaging. In this work, effective red UCL is achieved in the ternary sulfide by the introduction of Tm 3+ or Ho 3+ ions into Er 3+ doped NaYS 2 under 1550 nm excitation. The main emission peak is successfully tuned from green (NaYS 2 :Er 3+ ) to highly efficient red luminescence (NaYS 2 :Er 3+ ,Tm 3+ and NaYS 2 :Er 3+ ,Ho 3+ ). The maximum red-to-green emission intensity ratio (I R /I G ) increased by 31 and 80 times, respectively. The lifetime of 4 I 9/2 (Er 3+ ) level decreases significantly from 3432 μs (NaYS 2 :Er 3+ ) down to 636 (NaYS 2 :Er 3+ ,Tm 3+ ) and 423 μs (NaYS 2 :Er 3+ ,Ho 3+ ), respectively. This is due to the altered energy transfer pathways, resulting in the population of 4 F 9/2 (Er 3+ ). The mechanisms of UCL and energy transfer processes are further supported by fluorescence decay dynamic measurements. The results show the realization of red-emissive UCL in the promising NaYS 2 matrix, representing a new type of red UCL phosphors.