A warm white emission of Bi3+-Eu3+ and Bi3+-Sm3+ codoping Lu2Ge2O7 phosphors by energy transfer of Bi3+-sensitized Eu3+/Sm3+

In the last few years, multicolor-tunable phosphors, especially single-composition white-light-emitting phosphors, have attracted increasing attention and interest for UV-converted white LEDs. In this paper, Lu2Ge2O7: Bi3+ phosphor presents a doublet emission ranging from UV to visible spectrum with a high QE of 76% To obtain a warm white emission, we tried to codope Eu3+ or Sm3+ into Lu2Ge2O7 with Bi3+ ions. Multicolor-tunable emission colors of Bi3+-Eu3+ and Bi3+-Sm3+ codopecl Lu2Ge2O7 samples are adjusted from cold white light, warm white light, light pink, pink, to red by changing the Eu3+ or Se3+ doping concentration. Energy transfer process occurring from Bi3+ to Eu3+ or Sm3+ is discussed in detail and the corresponding eta(ETE) of Bi3+-Eu3+ and Bi3+ - Sm3+ can reach as high as 42% and 35%, respectively. This paper not only provides a novel UV-converted multicolor-tunable phosphor, but also discovery novel single-composition white-light-emitting phosphors for UV-converted white LEDs. (C) 2019 Published by Elsevier B.V.