High luminescence quantum efficiency of Eu^3C-doped SnO₂–SiO₂glasses due to excitation energy transfer from nano-sized SnO₂crystals

The strong Eu3+ photoluminescence in xSnO2–(100–ܨ)SiO2 derived bythe sol–gel method was reported. It was shown that Eu3+ ions were embedded in SnO2 nanocrystals (tetragonal, rutile) surrounded by a SiO2 glass matrix. Time-resolved photoluminescence spectra and excitation spectra revealed that Eu3+ ions could receive excitation energy from electron–hole pairs in SnO2 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 Eu3C ions. Absolute quantum luminescence efficiencies were found to be 60.5 (internal) and 26.7% (external).