Codopant ion-induced tunable upconversion emission in β-NaYF₄:Yb³⁺/Tm³⁺nanorods

Abstract

An innovative route to tune upconversion (UC) emission in β-NaYF(4):Yb(3+)/Tm(3+) nanorods through codoping a third rare-earth ion upon continuous wave excitation near 976 nm is reported. The dependence of UC emission on codopant concentration and environment temperature shows that tailored local environment and readjustable depopulation of excited-state ions are responsible for the tuning of UC luminescence. Codopant ions introduce a new distribution of active ions and a modified distance between Tm(3+) and Yb(3+) ions, making UC systems more sensitive to impurity ions than downconversion systems.

Synthesis, characterization and luminescent properties of europium complexes with 2,4,6‐tris‐(2‐pyridyl)‐s‐triazine as highly efficient sensitizers

“…Third, NO 3 – is just coordinated to rare earth ions and the ability to absorb and transfer energy is poor . There may be other reasons for the above‐mentioned phenomena and further investigations are needed.…”

Synthesis and Up‐conversion Luminescence of Yb3+/Ln3+ (Ln = Er,Tm,Ho) Co‐Doped Strontium Cerate by Pechini Method

“…Figure (a) shows the UC emission spectrum of the Sr 2 CeO 4 :Yb 3+ /Er 3+ sample excited at 980 nm. The emission bands centered at 532, 557, and 675 nm can be assigned to 2 H 11/2 → 4 I 15/2 (green), 2 S 3/2 → 4 I 15/2 (green), and 4 F 9/2 → 4 I 15/2 (red) transitions of Er 3+ , respectively . The total luminescence color, which can be coordinated in the Commission Internationale de L'Eclairage (CIE) Chromaticity Diagram as x = 0.3286, y = 0.6586, locates in the border of green region (point A in Fig.…”

“…In addition, the third Yb 3+ transfers populate the 1 G 4 excited state of Tm 3+ . Then the emissions from these populated states to the ground states take place, including the blue emission ( 1 G 4 → 3 H 6 ), red ( 1 G 4 → 3 F 4 , 3 H 4 → 3 H 6 ) emission of Tm 3+ ion . The whole process of Sr 2 CeO 4 :Yb 3+ /Tm 3+ can be expressed as following formulas: (1) 2 F 7/2 (Yb 3+ ) + 980 nm photon → 2 F 5/2 (Yb 3+ ); (2) 2 F 5/2 (Yb 3+ ) + 3 H 6 (Tm 3+ ) → 2 F 7/2 (Yb 3+ ) + 3 H 5 (Tm 3+ ) (ET1); (3) 3 H 5 (Tm 3+ ) → 3 F 4 (Tm 3+ ); (4) 2 F 5/2 (Yb 3+ ) + 3 F 4 (Tm 3+ ) → 2 F 7/2 (Yb 3+ ) + 3 F 2,3 (Tm 3+ ) (ET2); (5) 3 F 2,3 (Tm 3+ ) → 3 H 4 (Tm 3+ ), 3 H 4 (Tm 3+ ) → 3 H 6 (Tm 3+ , red); and (6) 2 F 5/2 (Yb 3+ ) + 3 H 4 (Tm 3+ ) → 2 F 7/2 (Yb 3+ ) + 1 G 4 (Tm 3+ ) (ET3), 1 G 4 (Tm 3+ ) → 3 H 6 (Tm 3+ , blue), 1 G 4 (Tm 3+ ) → 3 F 4 (Tm 3+ , red).…”

“…It is well known that UC efficiency is mainly dependent on the host material and doping ion, especially the former, a change of the host can enhance or decrease significantly the UC luminescent properties for it can strongly influence the transitions of the lanthanides, therefore ongoing research is mainly concerned with the quest for host materials with increased conversion efficiencies. The UC luminescence of rare earth ions has been investigated in various matrices, such as Gd 2 O 3 , In 2 O 3 , Bi 2 Ti 2 O 7 , NaGdF 4 , and NaYF 4 , etc. Among which NaYF 4 :Er 3+ ,Yb 3+ has been proved to give the strongest UC emissions.…”

Highly efficient NIR–NIR upconversion in potassium substituted CaMoO4:Tm3+, Yb3+ phosphor for potential biomedical applications

“…19,20 In UC based techniques, detection sensitivity depends on the luminescence intensity of the phosphor. 27 To date, hexagonal NaYF 4 is the most researched and efficient host material for green, red and blue UC in which NIR excitation is absorbed by the Yb 3+ ion and UC luminescence emitted by Er 3+ or Tm 3+ , respectively. Hence, the luminescence intensity enhancement of UCNPs is still a challenging topic.…”