Huge enhancement of upconversion luminescence by broadband dye sensitization of core/shell nanocrystals

Abstract

Upconversion nanocrystals (UCNCs) hold promise for bioimaging, solar cells, photocatalysis and volumetric displays. However, their upconversion luminescence intensities are usually low due to the weak and narrowband near-infrared absorption of lanthanide ions. Herein, we introduce and validate a strategy to hugely enhance upconversion luminescence intensity by using an organic near-infrared dye as an antenna to sensitize core/shell UCNCs. The dye can increase absorptivity and broaden the absorption spectrum of the UCNCs. Such dye sensitization, in combination with a core/shell structure, can tremendously enhance the upconversion luminescence (UCL) intensity of the UCNCs. The UCL intensity of dye-sensitized UCNCs excited at 820 nm is 800-folds higher than that of pure UCNCs excited at 980 nm. Further enhancement can be obtained by optimization of the dye emission and UCNC absorption spectral overlap. Moreover, the proposed approach can be extended to cover any part of the solar spectrum by using a set of dyes. This work provides new insights into the efficient enhancement of upconversion luminescence of the UCNCs and facilitates their applications.

Integration of IR‐808 Sensitized Upconversion Nanostructure and MoS2 Nanosheet for 808 nm NIR Light Triggered Phototherapy and Bioimaging

“…Some recent literatures reported that the NIR dye sensitization can markedly improve upconversion performance of various UCNPs . Accordingly, the NIR dyes have much higher absorption coefficients due to their wide absorption band and higher extinction coefficient than lanthanide ions . Furthermore, the NIR‐emissive peaks of IR‐808 overlap perfectly with the absorptivity of Yb 3+ and Nd 3+ ions, thus we envisage that a suitable combination of NIR dye and core–shell UCNPs with Nd 3+ /Yb 3+ codoped shell could achieve ideal upconversion luminescence (UCL) under low 808 nm excitation.…”

Gadolinium theranostics for the diagnosis and treatment of cancer

“…NIR dyes have a larger absorption coefficient than rare-earth nanoparticles. 51 There are also certain dyes that have an emission wavelength of 808 nm which overlaps with the absorption wavelength of Yb 3+ and Nd 3+ . This means the dyes can act as an antenna, improving the effectiveness of the UCNP.…”

Bright Blue, Green, and Red Luminescence from Dye-Sensitized Core@Shell Upconversion Nanophosphors under 800 nm Near-Infrared Light

“…Previously, our group reported the sub-20 nm-sized red-emitting NaGdF 4 :Yb,Ho,Ce@NaYF 4 :Nd,Yb@NaGdF 4 core@double-shell UCNPs and we showed in vivo UCL imaging and magnetic resonance imaging results utilizing the core@double-shell UCNPs [1]. Recently, NIR dye-sensitized UCNPs have been studied to significantly increase the absorption at around the 800 nm region and hugely enhance the emission intensity [20][21][22][23][24][25]. Wu's group synthesized C@S UCNPs and showed that the UCL from the C@S UCNPs was largely enhanced under 820 nm NIR excitation by the conjugation of IR-820 dye to the C@S UCNPs [21].…”

“…As described above, NIR dye-sensitization is beneficial to the enhancement of the luminescence from UCNPs. However, previous studies on dye-sensitized UCNPs were based on NaYF 4 -based blue-and green-emitting UCNPs, and non-NaYF 4 -based dye-sensitized UCNPs have not yet been studied [20][21][22][23][24][25]. In addition, to the best of our knowledge, no study has been reported on dye-sensitized red-emitting UCNPs.…”

“…Recently, NIR dye-sensitized UCNPs have been studied to significantly increase the absorption at around the 800 nm region and hugely enhance the emission intensity [20][21][22][23][24][25]. Wu's group synthesized C@S UCNPs and showed that the UCL from the C@S UCNPs was largely enhanced under 820 nm NIR excitation by the conjugation of IR-820 dye to the C@S UCNPs [21]. Prasad's group reported that the energy absorbed by the organic dye is efficiently transferred to Tm 3+ ions doped in the core UCNPs through Nd 3+ ions doped in the shell.…”