Bright white upconversion luminescence in rare-earth-ion-doped Y2O3 nanocrystals

Room temperature bright white upconversion (UC) luminescence in Yb3+-Tm3+-Er3+ ions doped Y2O3 nanocrystals was obtained under single-wavelength diode laser excitation of 976 nm. The white light consists of the blue, green, and red UC radiations which correspond to the transitions (1)G(4)-> H-3(6) of Tm3+, H-2(11/2)/S-4(3/2)-> I-4(15/2), and F-4(9/2)-> I-4(15/2) of Er3+ ions, respectively. The UC mechanisms were proposed based on spectral, kinetic, and pump power dependence analyses. The calculated color coordinates display that white light can be achieved in a wide range of pumping powers, which promises their potential applications in the field of displays, lasers, photonics, and biomedicine. (C) 2007 American Institute of Physics.