The kinetic limitation of anti-stokes luminescence of Er3+ and Yb3+ doped infrared upconversion materials

Abstract

Infrared-to-visible wave-length conversion in the Yb ¿· -Er ¿· doped phosphors system has been described by a simple three level model based on two ions mechanism. The excitation in the range of 900-1000 nm of an IR-photon is first absorbed by Yb ¿· ion as a sensitizer attributed to the resonant energy transition in Er ¿· ion from Ë ¿ ¾ Á ½ ¾ and ¾ Á ½ ¾ , respectively for green and red emission. The essential energy transfer processes in this system i.e. upconversion from Á ½½ ¾ and Á ½¿ ¾ , cross-relaxation from Ë ¿ ¾ and ¾ are taken into account. The limitations of the rate-equation approach are examined with a focus on the underlying dynamics of this rare-earth system.

Highly efficient NIR to NIR and VIS upconversion in Er3+ and Yb3+ doped in M2O2S (M = Gd, La, Y)

“…This discrepancy can be due to the difference in population path of each emitting state at different excitation power densities at different doping levels, which has also been proved in many other hosts. 47,48 The detailed explanation of the UC process in these UC phosphors will be explored in a later section.…”

Lanthanide-doped upconverting phosphors for bioassay and therapy

“…1), these lanthanide-doped illuminant materials are also referred to as anti-Stokes rule materials. [6][7][8][9][10][11][12][13] The use of NIR light as an excitation source for lanthanidedoped upconverting phosphors (UCPs) brings many benefits. One advantage is the high penetration depth in tissues, since biological tissues absorb light least in the NIR range (650 to 1000 nm) as opposed to the visible (350 to 700 nm) and infrared ranges (>1000 nm) where light is known to be strongly absorbed.…”