Quantum cutting downconversion by cooperative energy transfer from Bi3+to Yb3+in Y2O3phosphor

Bi 3+ and Yb 3+ codoped cubic Y 2 O 3 phosphors are prepared by pechini sol–gel method. Strong near-infrared (NIR) emission around 980 nm from Yb 3+ ( 2 F 5/2 → 2 F 7/2 ) is observed under ultraviolet light excitation. A broad excitation band ranging from 320 to 360 nm, owing to the 6s 2 → 6s6p transition of Bi 3+ ions, is recorded when the Yb 3+ emission is monitored, which suggests a very efficient energy transfer from Bi 3+ ions to Yb 3+ ions. The Yb 3+ concentration dependences of both the Bi 3+ and the Yb 3+ emissions are investigated. The decay curve of Bi 3+ emission under the excitation of 355 nm pulse laser is used to explore the Bi 3+ → Yb 3+ energy transfer process. Cooperative energy transfer (CET) is discussed as a possible mechanism for the near-infrared emission.