Visible and near infrared upconversion photoluminescence from Y2O3:Er3+, Yb3+, Li+ phosphors under 1532 nm excitation light

Visible and near-infrared upconversion luminescence from Y2O3 co-doped with Er3+, Yb3+ and Li+ phosphors under continuous excitation with 1532 nm light are reported. The upconversion emissions at 530-570 nm (green light emission region), and 640-700 nm (red light emission region) correspond to transitions from the S-4(3/2) to I-4(15/2) and (F-4(9/2) + I-4(9/2)) to I-4(15/2) electronic energy levels of the Er3+ ions respectively. The near infrared emissions at 900-1100 nm region correspond to inter-electronic energy levels transitions from I-4(11/2) to I-4(15/2) of Er3+ ions and F-2(5/2) to F-2(7/2) of Yb3+ ions. The role of Li+ and Yb3+ ions were to enhance the luminescence emission of these phosphors around 9, 7 and 11 times, respectively in comparison with only-erbium doped samples. The luminescence spectra of these phosphors remain unchanged when dispersed in deionized water, cholesterol and in bovine serum. (C) 2017 Published by Elsevier B.V.