Energy transfer to enhance the characteristics emission from lanthanide-doped nanocrystals

We report the improved characteristic emission of Er3+ ions by co-doping wide-band-gap SnO2 nanocrystals (NCs), which as sensitizers of Er3+ ions. It is found that the Er3+-related near infrared emission is enhanced by three orders of magnitude, which can be attributed to the effective energy transfer process occurs between SnO2 nanocrystals and Er3+ ions. Meanwhile, we also prepare the Er3+-Yb3+ co-doped NaYF4 NCs with Gd3+ dopant ions to obtain high-efficiency up-conversion emission by energy transfer from Yb3+ to Er3+. We demonstrate experimentally that Gd3+ dopant ions play key roles in the formation of β-NaYF4 NCs which can improve the energy transfer efficiency from Yb3+ to Er3+ obviously. Consequently, the up-conversion emission is enhanced by more than five times.