High luminescence quantum efficiency of Eu~(3+)-doped SnO_2-SiO_2 glasses due to excitation energy transfer from nano-sized SnO_2 crystals

摘要

The strong Eu~(3+) photoluminescence in xSnO_2-(100—x)SiO_2 derived by the sol-gel method was reported. It was shown that Eu~(3+) ions were embedded in SnO_2 nanocrystals (tetragonal, rutile) surrounded by a SiO_2 glass matrix. Time-resolved photoluminescence spectra and excitation spectra revealed that Eu~(3+) ions could receive excitation energy from electron-hole pairs in SnO_2 semiconductor nanocrystal, whose band-gap energy shifted to the higher energy side due to the quantum size effect, and was tuned to an optimum frequency for energy transfer to Eu~(3+) ions. Absolute quantum luminescence efficiencies were found to be 60.5 (internal) and 26.7% (external).