Carbon dot-mediated synthesis of NaYF4:Yb3+,Er3+@carbon dot composites with enhanced upconversion luminescence for temperature sensing

• Published in: RSC advances Vol. 15; no. 16; pp. 12797 - 12807
• Main Authors: Zou, Linlin, Yu, Ting, Sheng, Haoyang, Chen, Yeqing, Zeng, Qingguang
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 16.04.2025; The Royal Society of Chemistry
• Subjects: Carbon; Carbon dots; Chemistry; Composite materials; Emission; Erbium; Fluorescence; Fluorides; Hexagonal phase; Luminescence; Phase transitions; Sodium compounds; Upconversion; Ytterbium
• ISSN: 2046-2069; 2046-2069
• DOI: 10.1039/d5ra00874c

Upconversion (UC) nanocrystals and carbon dots (CDs) have emerged as significant subjects of research interest across various fields, including biomedicine, fluorescence sensing, and anti-counterfeiting. This study presents a novel method for preparing NaYF4:Yb3+,Er3+@CDs composites through the cubic-to-hexagonal phase transformation of NaYF4 mediated by CDs. The formation of these composites was successfully confirmed through morphological and structural analyses. Notably, the composites were found to enhance UC emission and prolong luminescence lifetime, with these effects being dependent on the quantity of CDs used. The experimental results indicate that the enhanced UC emission in the composites is primarily due to the interception of quenching centers, such as hydroxyl (OH−) groups. Furthermore, these composites with improved UC emission have the potential to serve as highly sensitive optical thermometers based on the fluorescence intensity ratio technique, with optimal green emissions at 298 K and a maximum relative sensitivity of 1.08 K−1. This work paves the way for advancements in UC luminescence and establishes a foundation for the design and fabrication of high-efficiency UC materials with potential applications in optical temperature sensing.