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Depth-profiling of Yb3+ sensitizer ions in NaYF4 upconversion nanocrystals


Enhancing the efficiency of upconversion nanoparticles (UCNPs) and therefore their brightness is the critical goal for this emerging material to meet growing demands in many potential applications including sensing, imaging, solar energy conversion and photonics. The distribution of the photon sensitizer and activator ions that form a network of energy transfer systems within each single UCNP are vital for understanding and optimizing their optical properties. Here we employ synchrotron-based X-ray Photoelectron Spectroscopy (XPS) to characterize the depth distribution of Yb3+ sensitizer ions in host NaYF4 nanoparticles and systematically correlate the structure with the optical properties for a range of UCNPs with different sizes and doping concentrations. We find a radical gradient distribution of Yb3+ from the core to the surface of the NaYF4 nanoparticles, regardless of their size or sensitizer’s concentration. Energy dispersive X-ray Spectroscopy (EDS) was also used to further confirm the distribution of the sensitizer ions in the host matrix. These results have profound implications for the upconversion optical property variations.

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Publication details

The article was received on 28 Feb 2017, accepted on 05 May 2017 and first published on 08 May 2017

Article type: Communication
DOI: 10.1039/C7NR01456B
Citation: Nanoscale, 2017, Accepted Manuscript
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    Depth-profiling of Yb3+ sensitizer ions in NaYF4 upconversion nanocrystals

    X. Xu, C. Clarke, C. Ma, G. Casillas, M. Das, M. Guan, D. Liu, L. Wang, A. Tadich, Y. Du, C. Ton-That and D. Jin, Nanoscale, 2017, Accepted Manuscript , DOI: 10.1039/C7NR01456B

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