Yang Zhengwen, Yang Jianzhi, Qiu Jianbei, Song Zhiguo
College of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, 650093, China.
Phys Chem Chem Phys. 2017 Dec 6;19(47):31997-32006. doi: 10.1039/c7cp06622h.
Comprehensive investigations of near infrared (NIR) downshift and visible upconversion luminescence (UCL) mechanisms were carried out for Yb single-doped and Er,Yb co-doped SiO inverse opals under excitation at 256, 378, 520 and 980 nm. NIR emission at 976 nm from the Yb-O charge transfer state and UCL emission at 500 nm due to the cooperative emission of two Yb ions were observed in SiO:Yb inverse opal upon excitation at 256 and 980 nm, respectively. The cooperative UCL of two Yb ions was suppressed due to the photon trap created by the photonic band gap. For the SiO:Er,Yb inverse opals, NIR emission of Yb at 976 nm and of Er at 1534 nm were observed upon excitation at 256, 378 and 520 nm, respectively. Upon excitation at 378 and 520 nm, the 976 nm NIR emission of Yb does not arise from (H/S) + 2Yb(F) → Er(I) + 2Yb(F) traditional quantum cutting. The NIR emission of Yb at 976 nm may be due to the Er(H) + Yb(F) → Yb(F) + Er(I) cross-relaxation energy transfer process upon excitation at 520 nm. The NIR emission of Yb at 976 nm may arise from the cross-relaxation energy transfer of Er(G) + Yb(F) → Yb(F) + Er(F) and Er(F) + Yb(F) → Yb(F) + Er(I) upon excitation at 378 nm.
对Yb单掺杂和Er、Yb共掺杂的SiO反蛋白石在256、378、520和980 nm激发下的近红外（NIR）下移和可见上转换发光（UCL）机制进行了全面研究。在SiO:Yb反蛋白石中，分别在256和980 nm激发下，观察到了来自Yb-O电荷转移态的976 nm近红外发射以及由于两个Yb离子的协同发射而产生的500 nm上转换发光。由于光子带隙产生的光子陷阱，两个Yb离子的协同上转换发光受到抑制。对于SiO:Er、Yb反蛋白石，分别在256、378和520 nm激发下，观察到了Yb在976 nm处的近红外发射和Er在1534 nm处的近红外发射。在378和520 nm激发下，Yb在976 nm处的近红外发射并非源于传统的量子切割（H/S）+2Yb(F)→Er(I)+2Yb(F)。Yb在976 nm处的近红外发射可能是由于在520 nm激发下发生的Er(H)+Yb(F)→Yb(F)+Er(I)交叉弛豫能量转移过程。Yb在976 nm处的近红外发射可能源于在378 nm激发下发生的Er(G)+Yb(F)→Yb(F)+Er(F)和Er(F)+Yb(F)→Yb(F)+Er(I)交叉弛豫能量转移。
