摘要
An innovative upconversion (UC) emissions route of Er3+ by Yb3+-Mn2+ dimer sensitizing in Er3+-Mn2+:Ybb>3b>Alb>5b>Ob>12b> (YbAG) nanocrystals is reported here, which resulted in the selective enhancement of green UC emission and suppression of red UC emission by a 976 nm laser diode excitation. By codoping of Mn2+, the green UC emission intensity increased about 260 times, while the red UC emission intensity decreased about 20 times than that of Er3+:YbAG nanocrystals. It indicates that the green enhancement and red suppression arise from the high excited state energy transfer with |2Fb>7/2b>, 4Tb>1gb>> (Yb3+-Mn2+ dimer) to the 4Fb>7/2b> (Er3+), which partly decreases the nonradiative processes happened in the lower levels of Er3+. The proposed sensitizing route here may constitute a promising step to realize high-efficient UC emissions of rare-earth ions doped oxides and significantly extend their scope of applications.