Controlled Synthesis of Monodisperse Hexagonal NaYF4:Yb/Er Nanocrystals with Ultrasmall Size and Enhanced Upconversion Luminescence
The ability to synthesize upconversion nanocrystals (UCNCs) with tailored upconversion luminescence and controlled size is of great importance for biophotonic applications. However, until now, limited success has been met to prepare bright, ultrasmall, and monodispersed β-NaYF4:Yb3+/Er3+ UCNCs. In t...
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MDPI AG
2017-12-01
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| Series: | Molecules |
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| Online Access: | https://www.mdpi.com/1420-3049/22/12/2113 |
| _version_ | 1828480987941568512 |
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| author | Hui Li Lei Xu Guanying Chen |
| author_facet | Hui Li Lei Xu Guanying Chen |
| author_sort | Hui Li |
| collection | DOAJ |
| description | The ability to synthesize upconversion nanocrystals (UCNCs) with tailored upconversion luminescence and controlled size is of great importance for biophotonic applications. However, until now, limited success has been met to prepare bright, ultrasmall, and monodispersed β-NaYF4:Yb3+/Er3+ UCNCs. In this work, we report on a synthetic method to produce monodisperse hexagonal NaYF4:Yb3+/Er3+ nanocrystals of ultrasmall size (5.4 nm) through a precise control of the reaction temperature and the ratio of Na+/Ln3+/F−. We determined the optimum activator concentration of Er3+ to be 6.5 mol % for these UCNCs, yielding about a 5-fold higher upconversion luminescence (UCL) intensity than the commonly used formula of NaYF4:30% Yb3+/2% Er3+. Moreover, a thin epitaxial shell (thickness, 1.9 nm) of NaLnF4 (Ln = Y, Gd, Lu) was grown onto these ultrasmall NaYF4:Yb3+/Er3+ NCs, enhancing its UCL by about 85-, 70- and 50-fold, respectively. The achieved sub-10-nm core and core–shell hexagonal NaYF4:Yb3+/Er3+ UCNCs with enhanced UCL have strong potential applications in bioapplications such as bioimaging and biosensing. |
| first_indexed | 2024-12-11T07:47:42Z |
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| institution | Directory Open Access Journal |
| issn | 1420-3049 |
| language | English |
| last_indexed | 2024-12-11T07:47:42Z |
| publishDate | 2017-12-01 |
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| record_format | Article |
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| spelling | doaj.art-f4d80659344045ebbde47f6aa22d9a0e2022-12-22T01:15:25ZengMDPI AGMolecules1420-30492017-12-012212211310.3390/molecules22122113molecules22122113Controlled Synthesis of Monodisperse Hexagonal NaYF4:Yb/Er Nanocrystals with Ultrasmall Size and Enhanced Upconversion LuminescenceHui Li0Lei Xu1Guanying Chen2MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering & Key Laboratory of Micro-Systems and Micro-Structures, Ministry of Education, Harbin Institute of Technology, Harbin 150001, ChinaMIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering & Key Laboratory of Micro-Systems and Micro-Structures, Ministry of Education, Harbin Institute of Technology, Harbin 150001, ChinaMIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering & Key Laboratory of Micro-Systems and Micro-Structures, Ministry of Education, Harbin Institute of Technology, Harbin 150001, ChinaThe ability to synthesize upconversion nanocrystals (UCNCs) with tailored upconversion luminescence and controlled size is of great importance for biophotonic applications. However, until now, limited success has been met to prepare bright, ultrasmall, and monodispersed β-NaYF4:Yb3+/Er3+ UCNCs. In this work, we report on a synthetic method to produce monodisperse hexagonal NaYF4:Yb3+/Er3+ nanocrystals of ultrasmall size (5.4 nm) through a precise control of the reaction temperature and the ratio of Na+/Ln3+/F−. We determined the optimum activator concentration of Er3+ to be 6.5 mol % for these UCNCs, yielding about a 5-fold higher upconversion luminescence (UCL) intensity than the commonly used formula of NaYF4:30% Yb3+/2% Er3+. Moreover, a thin epitaxial shell (thickness, 1.9 nm) of NaLnF4 (Ln = Y, Gd, Lu) was grown onto these ultrasmall NaYF4:Yb3+/Er3+ NCs, enhancing its UCL by about 85-, 70- and 50-fold, respectively. The achieved sub-10-nm core and core–shell hexagonal NaYF4:Yb3+/Er3+ UCNCs with enhanced UCL have strong potential applications in bioapplications such as bioimaging and biosensing.https://www.mdpi.com/1420-3049/22/12/2113ultrasmall sizeoptimum concentrationupconversion luminescencecore–shell structure |
| spellingShingle | Hui Li Lei Xu Guanying Chen Controlled Synthesis of Monodisperse Hexagonal NaYF4:Yb/Er Nanocrystals with Ultrasmall Size and Enhanced Upconversion Luminescence Molecules ultrasmall size optimum concentration upconversion luminescence core–shell structure |
| title | Controlled Synthesis of Monodisperse Hexagonal NaYF4:Yb/Er Nanocrystals with Ultrasmall Size and Enhanced Upconversion Luminescence |
| title_full | Controlled Synthesis of Monodisperse Hexagonal NaYF4:Yb/Er Nanocrystals with Ultrasmall Size and Enhanced Upconversion Luminescence |
| title_fullStr | Controlled Synthesis of Monodisperse Hexagonal NaYF4:Yb/Er Nanocrystals with Ultrasmall Size and Enhanced Upconversion Luminescence |
| title_full_unstemmed | Controlled Synthesis of Monodisperse Hexagonal NaYF4:Yb/Er Nanocrystals with Ultrasmall Size and Enhanced Upconversion Luminescence |
| title_short | Controlled Synthesis of Monodisperse Hexagonal NaYF4:Yb/Er Nanocrystals with Ultrasmall Size and Enhanced Upconversion Luminescence |
| title_sort | controlled synthesis of monodisperse hexagonal nayf4 yb er nanocrystals with ultrasmall size and enhanced upconversion luminescence |
| topic | ultrasmall size optimum concentration upconversion luminescence core–shell structure |
| url | https://www.mdpi.com/1420-3049/22/12/2113 |
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