Condensed Matter Science and Technology Institute, Harbin Institute of Technology, Harbin, China.
Opt Lett. 2013 Jun 15;38(12):2101-3. doi: 10.1364/OL.38.002101.
NaYF4:Yb, Er/NaYF4 core-shell nanocrystals with different thickness shells were synthesized. The correlation between shell thickness and upconversion (UC) luminescence intensity was investigated experimentally and theoretically. We found that the UC fluorescence intensity of the core-shell nanocrystals is enhanced exponentially with shell thickness (d) in the form of (1-0.9 exp(-d/d0). For our core-shell nanocrystals, the d0 was determined as about 5.5 nm, corresponding to an enhancement of about 12 times for the 540 nm emission intensity. The d0 may be treated as the optimized shell thickness, which represents a balance between the conflict requirements of strong UC fluorescence intensity and small total crystal size for bioapplications.
NaYF4:Yb, Er/NaYF4 核壳纳米晶具有不同厚度的壳。实验和理论研究了壳厚与上转换（UC）发光强度的关系。我们发现核壳纳米晶的 UC 荧光强度随壳厚（d）呈指数增强，形式为（1-0.9 exp(-d/d0)。对于我们的核壳纳米晶，d0 约为 5.5nm，对应于 540nm 发射强度增强约 12 倍。d0 可以看作是优化的壳厚，它代表了生物应用中强 UC 荧光强度和小总晶体尺寸的冲突要求之间的平衡。
