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Activation of the surface dark-layer to enhance upconversion in a thermal field


Thermal quenching, in which light emission experiences a loss with increasing temperature, broadly limits luminescent efficiency at higher temperature in optical materials, such as lighting phosphors1,2,3 and fluorescent probes4,5,6. Thermal quenching is commonly caused by the increased activity of phonons that leverages the non-radiative relaxation pathways. Here, we report a kind of heat-favourable phonons existing at the surface of lanthanide-doped upconversion nanomaterials to combat thermal quenching. It favours energy transfer from sensitizers to activators to pump up the intermediate excited-state upconversion process. We identify that the oxygen moiety chelating Yb3+ ions, [Yb···O], is the key underpinning this enhancement. We demonstrate an approximately 2,000-fold enhancement in blue emission for 9.7 nm Yb3+-Tm3+ co-doped nanoparticles at 453 K. This strategy not only provides a powerful solution to illuminate the dark layer of ultra-small upconversion nanoparticles, but also suggests a new pathway to build high-efficiency upconversion systems.

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Fig. 1: Schematic illustration of the surface-phonon-enhanced upconversion process.
Fig. 2: Surface-phonon-enhanced upconversion in different sensitizer−activator systems.
Fig. 3: Surface engineering to investigate surface-phonon-enhanced upconversion.
Fig. 4: Surface phonons significantly enhance the brightness of ultra-small upconversion nanoparticles.


  1. 1.

    Kim, Y. H. et al. A zero-thermal-quenching phosphor. Nat. Mater. 16, 543–550 (2017).

    ADS  Article  Google Scholar 

  2. 2.

    Wang, L. et al. Ca1–xLi x Al1–xSi1+xN3:Eu2+ solid solutions as broadband, color-tunable and thermally robust red phosphors for superior color rendition white light-emitting diodes. Light Sci. Appl. 5, e16155 (2016).

  3. 3.

    Zhu, H. et al. Highly efficient non-rare-earth red emitting phosphor for warm white light-emitting diodes. Nat. Commun. 5, 4312 (2014).

    Google Scholar 

  4. 4.

    Liang, R. et al. A temperature sensor based on CdTe quantum dots-layered double hydroxide ultrathin films via layer-by-layer assembly. Chem. Commun. 49, 969–971 (2013).

    Article  Google Scholar 

  5. 5.

    Liu, D. et al. Emission stability and reversibility of upconversion nanocrystals. J. Mater. Chem. C 4, 9227–9234 (2016).

    ADS  Article  Google Scholar 

  6. 6.

    Zhu, X. et al. Temperature-feedback upconversion nanocomposite for accurate photothermal therapy at facile temperature. Nat. Commun. 7, 10437 (2016).

    ADS  Article  Google Scholar 

  7. 7.

    Auzel, F. & Chen, Y. The effective frequency in multiphonon processes: Differences for energy transfers or side-bands and non-radiative decay. J. Lumin. 66, 224–227 (1995).

    Article  Google Scholar 

  8. 8.

    Xue, X. et al. Size-dependent upconversion luminescence and quenching mechanism of LiYF4: Er3+/Yb3+ nanocrystals with oleate ligand adsorbed. Opt. Mater. Express 3, 989–999 (2013).

    Article  Google Scholar 

  9. 9.

    Lim, S. F., Ryu, W. S. & Austin, R. H. Particle size dependence of the dynamic photophysical properties of NaYF4: Yb, Er nanocrystals. Opt. Express 18, 2309–2316 (2010).

    ADS  Article  Google Scholar 

  10. 10.

    Liu, Y. et al. Amplified stimulated emission in upconversion nanoparticles for super-resolution nanoscopy. Nature 543, 229–233 (2017).

    ADS  Article  Google Scholar 

  11. 11.

    Gargas, D. J. et al. Engineering bright sub-10-nm upconverting nanocrystals for single-molecule imaging. Nat. Nanotech. 9, 300–305 (2014).

    ADS  Article  Google Scholar 

  12. 12.

    Brites, C. D. et al. Instantaneous ballistic velocity of suspended Brownian nanocrystals measured by upconversion nanothermometry. Nat. Nanotech. 11, 851–856 (2016).

    ADS  Article  Google Scholar 

  13. 13.

    Xu, J. et al. Near-infrared-triggered photodynamic therapy with multitasking upconversion nanoparticles in combination with checkpoint blockade for immunotherapy of colorectal cancer. ACS Nano 11, 4463–4474 (2017).

    Article  Google Scholar 

  14. 14.

    Wu, X. et al. Dye-sensitized core/active shell upconversion nanoparticles for optogenetics and bioimaging applications. ACS Nano 10, 1060–1066 (2016).

    Article  Google Scholar 

  15. 15.

    Zhao, J. et al. Single-nanocrystal sensitivity achieved by enhanced upconversion luminescence. Nat. Nanotech. 8, 729–734 (2013).

    ADS  Article  Google Scholar 

  16. 16.

    Lu, Y. et al. Tunable lifetime multiplexing using luminescent nanocrystals. Nat. Photon. 8, 32–36 (2014).

    ADS  Article  Google Scholar 

  17. 17.

    Zou, W. et al. Broadband dye-sensitized upconversion of near-infrared light. Nat. Photon. 6, 560–564 (2012).

    ADS  Article  Google Scholar 

  18. 18.

    Wang, F. et al. Simultaneous phase and size control of upconversion nanocrystals through lanthanide doping. Nature 463, 1061–1065 (2010).

    ADS  Article  Google Scholar 

  19. 19.

    Deng, R. et al. Temporal full-colour tuning through non-steady-state upconversion. Nat. Nanotech. 10, 237–242 (2015).

    ADS  Article  Google Scholar 

  20. 20.

    Wu, S., Ning, Y., Chang, J. & Zhang, S. Upconversion photoluminescence enhancement and modulation of NaYF4: Yb, Er through using different ligands. J. Lumin. 143, 492–497 (2013).

    Article  Google Scholar 

  21. 21.

    Bogdan, N., Vetrone, F., Ozin, G. A. & Capobianco, J. A. Synthesis of ligand-free colloidally stable water dispersible brightly luminescent lanthanide-doped upconverting nanoparticles. Nano Lett. 11, 835–840 (2011).

    ADS  Article  Google Scholar 

  22. 22.

    Shan, J., Uddi, M., Yao, N. & Ju, Y. Anomalous Raman scattering of colloidal Yb3+, Er3+ codoped NaYF4 nanophosphors and dynamic probing of the upconversion luminescence. Adv. Funct. Mater. 20, 3530–3537 (2010).

    Article  Google Scholar 

  23. 23.

    Panitz, J.-C., Mayor, J.-C., Grob, B. & Durisch, W. A Raman spectroscopic study of rare earth mixed oxides. J. Alloy Compd. 303, 340–344 (2000).

    Article  Google Scholar 

  24. 24.

    Levy, E. S. et al. Energy-looping nanoparticles: harnessing excited-state absorption for deep-tissue imaging. ACS Nano 10, 8423–8433 (2016).

    Article  Google Scholar 

  25. 25.

    Li, D., Shao, Q., Dong, Y. & Jiang, J. Anomalous temperature-dependent upconversion luminescence of small-sized NaYF4: Yb3+, Er3+ nanoparticles. J. Phys. Chem. C 118, 22807–22813 (2014).

    Article  Google Scholar 

  26. 26.

    Liu, G. et al. Confinement of electron–phonon interaction on luminescence dynamics in nanophosphors of Er3+: Y2O2S. J. Phys. Chem. B 171, 123–132 (2003).

    Google Scholar 

  27. 27.

    Wang, F., Wang, J. & Liu, X. Direct evidence of a surface quenching effect on size-dependent luminescence of upconversion nanoparticles. Angew. Chem. Int Ed. Engl. 49, 7456–7460 (2010).

    Article  Google Scholar 

  28. 28.

    Vetrone, F. et al. Temperature sensing using fluorescent nanothermometers. ACS Nano 4, 3254–3258 (2010).

    Article  Google Scholar 

  29. 29.

    Lu, J. et al. One-step protein conjugation to upconversion nanoparticles. Anal. Chem. 87, 10406–10413 (2015).

    Article  Google Scholar 

  30. 30.

    Zheng, W. et al. Sub-10 nm lanthanide-doped CaF2 nanoprobes for time-resolved luminescent biodetection. Angew. Chem. Int Ed. 52, 6671–6676 (2013).

    ADS  Article  Google Scholar 

  31. 31.

    Zhao, J. et al. Upconversion luminescence with tunable lifetime in NaYF4:Yb,Er nanocrystals: role of nanocrystal size. Nanoscale 5, 944–952 (2013).

    ADS  Article  Google Scholar 

  32. 32.

    Liu, H. et al. Balancing power density based quantum yield characterization of upconverting nanoparticles for arbitrary excitation intensities. Nanoscale 5, 4770–4775 (2013).

    ADS  Article  Google Scholar 

  33. 33.

    Zhang, F. et al. Shape, size, and phase-controlled rare-earth fluoride nanocrystals with optical up-conversion properties. Chem. Eur. J. 15, 11010–11019 (2009).

    Article  Google Scholar 

  34. 34.

    Perdew, J. P., Burke, K. & Ernzerhof, M. Generalized gradient approximation made simple. Phys. Rev. Lett. 77, 3865–3868 (1996).

    ADS  Article  Google Scholar 

  35. 35.

    Blöchl, P. E. Projector augmented-wave method. Phys. Rev. B 50, 17953 (1994).

    ADS  Article  Google Scholar 

  36. 36.

    Kresse, G. & Furthmüller, J. Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Phys. Rev. B 54, 11169–11186 (1996).

    ADS  Article  Google Scholar 

  37. 37.

    Liu, D. et al Three-dimensional controlled growth of monodisperse sub-50 nm heterogeneous nanocrystals. Nat. Commun. 7, 10254 (2016).

    ADS  Article  Google Scholar 

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This project is primarily supported by the Australian Research Council (ARC) Discovery Early Career Researcher Award Scheme (J.Z., DE180100669), Chancellor’s Postdoctoral Fellowship Scheme at the University of Technology Sydney (J.Z.), and ARC Future Fellowship Scheme (D.J., FT 130100517).

Author information




J.Z. and D.J. conceived the project and designed the experiments; S.W., J.L., and J.Z. conducted synthesis; C.C. and J.Z. performed the security ink printing and imaging; S.A.T. carried out simulation work; W.R. conducted the surface modification; C.M. and F.W. built the optical testing system; J.Z. conducted the spectroscopic characterization; J.Z. and D.J. prepared the figures, data analysis, supplementary information sections, and wrote the manuscript with input from other authors.

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Correspondence to Jiajia Zhou or Dayong Jin.

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The authors declare no competing financial interests.

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Supplementary Information

Supplementary Data; Supplementary Figures 1–7; Supplementary Tables 1–2; Supplementary Reference 1.

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Zhou, J., Wen, S., Liao, J. et al. Activation of the surface dark-layer to enhance upconversion in a thermal field. Nature Photon 12, 154–158 (2018).

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