High luminescence quantum efficiency of Eu3+-doped SnO2-SiO2 glasses due to excitation energy transfer from nano-sized SnO2 crystals

The strong Eu3+ photoluminescence in xSnO2-(100−x)SiO2 derived by the 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 Eu3+ ions. Absolute quantum luminescence efficiencies were found to be 60.5 (internal) and 26.7% (external).