Near-infrared excited luminescence and in vitro imaging of HeLa cells by using Mn²⁺ enhanced Tb³⁺ and Yb³⁺ cooperative upconversion in NaYF₄ nanocrystals

Abstract

To improve the Tb3+ upconversion emission intensity, a new approach, i.e. Mn2+ co-doping, has been proposed and verified in this work. The significant enhancement of the emission intensity as a result of the introduction of Mn2+ ions was observed.

Nonlinear photoresponse of NaYF4:Yb,Er@NaYF4 nanocrystals under green CW excitation: a comprehensive study

“…8 However, anti-Stokes wavelength shiing for UCNPs appears even at low-intensity excitations. At present, based on interesting properties of UCNPs, there are various applications such as laser materials, 9 photolithography, 10 optical switching, 11 nanophotonic energy storage, 12 imaging 13 and bio detections. 14 Many studies on UCNPs have focused on nonlinear processes under different NIR excitations.…”

Up-conversion emission in transition metal and lanthanide co-doped systems: dimer sensitization revisited

“…Co-doping lanthanide (Ln) based nanoparticles with transition metals (TM) is intensively exploited in the search for upconversion (UC) systems with high quantum efficiency and modulated colour 1 – 8 . TM, especially Mo(6 +), but also W(6 +) (both considered as d 0 centred anion Mo/WO 4 2− ), d 5 Mn(2 +) and Fe(3 +) determine significant intensity enhancement paired with colour change and photon order modification of Ln UC emission in many hosts such as Yb 2 Ti 2 O 7 , YbAG 9 , TiO 2 and Gd 2 O 3 , Bi 7 Ti 4 NbO 21 10 , Al 2 O 3 11 , 12 , Y 2 Mo 4 O 15 13 , ZnO 14 , NaY(Lu)F 4 15 , 16 and KZnF 3 17 . As such, Mo co-doping enhances the Er UC emission by two orders of magnitude coupled with a colour change from red (Mo free) to green 9 .…”

Photon upconversion through triplet exciton-mediated energy relay

“…To this end, considerable effort has been devoted to strategies for lanthanide emitters without long-lived intermediate energy levels 33 – 37 . Specifically, upconversion luminescence from Tb 3+ or Eu 3+ ions has been achieved through cooperative sensitization upconversion 38 – 41 or dimerization sensitization 42 , 43 . However, these upconversion processes often suffer from low conversion efficiency and weak emission.…”