Design and achieving mechanism of upconversion white emission based on Yb3+/Tm3+/Er3+ tri-doped KY3F10 nanocrystals

KY3F10:Yb3+/Tm3+/Er3+ upconversion nanocrystals are synthesized via a simple hydrothermal procedure. The nanocrystals emit the near equal energy white light with high brightness and favorable color balance when excited using a 980 nm continuous wave diode laser. The research of upconversion mechanism indicates that in addition to the energy transfer processes from Yb3+ to Tm3+ and Er3+, respectively, there exists a new process 1G4 (Tm3+) + 4I11/2 (Er3+) → 3H4 (Tm3+) + 4S3/2 (Er3+).