TY  - JOUR
AB  - © 2018 The Author(s). 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 phosphors 1-3 and fluorescent probes 4-6 . 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.
AU  - Zhou, J
AU  - Wen, S
AU  - Liao, J
AU  - Clarke, C
AU  - Tawfik, SA
AU  - Ren, W
AU  - Mi, C
AU  - Wang, F
AU  - Jin, D
DA  - 2018/03/01
DO  - 10.1038/s41566-018-0108-5
EP  - 158
JO  - Nature Photonics
PY  - 2018/03/01
SP  - 154
TI  - Activation of the surface dark-layer to enhance upconversion in a thermal field
VL  - 12
Y1  - 2018/03/01
Y2  - 2026/06/12
ER  -