TY - JOUR
T1 - Near-infrared to visible upconversion in Er 3+ and Yb 3+ codoped Lu 2O 3 nanocrystals
T2 - Enhanced red color upconversion and three-photon process in green color upconversion
AU - Li, Yanping
AU - Zhang, Jiahua
AU - Zhang, Xia
AU - Luo, Yongshi
AU - Ren, Xinguang
AU - Zhao, Haifeng
AU - Wang, Xiaojun
AU - Sun, Lingdong
AU - Yan, Chunhua
PY - 2009/3/19
Y1 - 2009/3/19
N2 - The synthesis and upconversion luminescence properties upon a 980 nm pump of cubic Lu 1.88Yb 0.1Er 0.02O 3 nanocrystals with various shapes, e.g., nanorods, nanosheets, and nanoparticles, are studied. It is observed that with decreasing size of the nanocrystals, the relative intensity of the upconverted red emission (Er 3+: 4F 9/2 f 4I 15/2) to the green one (Er 3+: ( 2H 11/2, 4S 3/2) f 4I 15/2) is increased, and a three-photon process involved in the green upconversion, as described by 4F 9/2(Er) + 2F 5/2 (Yb) f 2H 9/2 (Er) + 2F 7/2 (Yb), is synchronously enhanced. An analysis based on steady-state rate equations indicates that the results can be induced by a large 4I 11/2 f 4I 13/2 nonradiative relaxation rate with a small 4F 9/2 f 4I 9/2 nonradiative relaxation rate. The large 4I 11/2 f 4I 13/2 nonradiative relaxation rate is attributed to the occurrence of efficient cross energy transfer to OH - surface group due to the good energy match. As the size of the nanocrystals decreases, the relative surface area is increased, increasing the number of OH - group that can attach to the surface, therefore, enhancing the 4I 11/2 f 4I 13/2 nonradiative relaxation rate through cross energy transfer to OH - surface group.
AB - The synthesis and upconversion luminescence properties upon a 980 nm pump of cubic Lu 1.88Yb 0.1Er 0.02O 3 nanocrystals with various shapes, e.g., nanorods, nanosheets, and nanoparticles, are studied. It is observed that with decreasing size of the nanocrystals, the relative intensity of the upconverted red emission (Er 3+: 4F 9/2 f 4I 15/2) to the green one (Er 3+: ( 2H 11/2, 4S 3/2) f 4I 15/2) is increased, and a three-photon process involved in the green upconversion, as described by 4F 9/2(Er) + 2F 5/2 (Yb) f 2H 9/2 (Er) + 2F 7/2 (Yb), is synchronously enhanced. An analysis based on steady-state rate equations indicates that the results can be induced by a large 4I 11/2 f 4I 13/2 nonradiative relaxation rate with a small 4F 9/2 f 4I 9/2 nonradiative relaxation rate. The large 4I 11/2 f 4I 13/2 nonradiative relaxation rate is attributed to the occurrence of efficient cross energy transfer to OH - surface group due to the good energy match. As the size of the nanocrystals decreases, the relative surface area is increased, increasing the number of OH - group that can attach to the surface, therefore, enhancing the 4I 11/2 f 4I 13/2 nonradiative relaxation rate through cross energy transfer to OH - surface group.
UR - http://www.scopus.com/inward/record.url?scp=65249176219&partnerID=8YFLogxK
U2 - 10.1021/jp810275t
DO - 10.1021/jp810275t
M3 - Article
AN - SCOPUS:65249176219
SN - 1932-7447
VL - 113
SP - 4413
EP - 4418
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 11
ER -