Quantum cutting downconversion by cooperative energy transfer from Bi3+ to Yb3+ in Y2O3 phosphor

Abstract

Bi3+ and Yb3+ codoped cubic Y2O3 phosphors are prepared by pechini sol–gel method. Strong near-infrared (NIR) emission around 980 nm from Yb3+ (2F5/2 →2 F7/2) is observed under ultraviolet light excitation. A broad excitation band ranging from 320 to 360 nm, owing to the 6s2 → 6s6p transition of Bi3+ ions, is recorded when the Yb3+ emission is monitored, which suggests a very efficient energy transfer from Bi3+ ions to Yb3+ ions. The Yb3+ concentration dependences of both the Bi3+ and the Yb3+ emissions are investigated. The decay curve of Bi3+ emission under the excitation of 355 nm pulse laser is used to explore the Bi3+ → Yb3+ energy transfer process. Cooperative energy transfer (CET) is discussed as a possible mechanism for the near-infrared emission.