X-ray-charged bright persistent luminescence in NaYF4:Ln3+@NaYF4 nanoparticles for multidimensional optical information storage

NaYF4:Ln(3+), due to its outstanding upconversion characteristics, has become one of the most important luminescent nanomaterials in biological imaging, optical information storage, and anticounterfeiting applications. However, the large specific surface area of NaYF4:Ln(3+) nanoparticles generally leads to serious nonradiative transitions, which may greatly hinder the discovery of new optical functionality with promising applications. In this paper, we report that monodispersed nanoscale NaYF4:Ln(3+), unexpectedly, can also be an excellent persistent luminescent (PersL) material. The NaYF4:Ln(3+) nanoparticles with surface-passivated core-shell structures exhibit intense X-ray-charged PersL and narrow-band emissions tunable from 480 to 1060 nm. A mechanism for PersL in NaYF4:Ln(3+) is proposed by means of thermoluminescence measurements and host-referred binding energy (HRBE) scheme, which suggests that some lanthanide ions (such as Tb) may also act as effective electron traps to achieve intense PersL. The uniform and spherical NaYF4:Ln(3+) nanoparticles are dispersible in solvents, thus enabling many applications that are not accessible for traditional PersL phosphors. A new 3-dimensional (2 dimensions of planar space and 1 dimension of wavelength) optical information-storage application is demonstrated by inkjet-printing multicolor PersL nanoparticles. The multicolor persistent luminescence, as an emerging and promising emissive mode in NaYF4:Ln(3+), will provide great opportunities for nanomaterials to be applied to a wider range of fields. Core-shelled nanoparticles NaYF4:Ln(3+)@NaYF4 with multicolor narrow-band persistent luminescence enable a new multidimensional optical information-storage technology.

Automated summary

Monodispersed nanoscale NaYF4:Ln(3+) nanoparticles with surface-passivated core-shell structures exhibit intense X-ray-charged persistent luminescence and narrow-band emissions tunable from 480 to 1060 nm. The mechanism for persistent luminescence in NaYF4:Ln(3+) is proposed through thermoluminescence measurements and the host-referred binding energy (HRBE) scheme, suggesting the role of lanthanide ions as effective electron traps. These uniform and spherical nanoparticles are dispersible in solvents, enabling new applications such as 3-dimensional optical information storage and inkjet-printing multicolor persistent luminescent nanoparticles.