Single band upconversion mechanisms of Er3+/Yb3+:ZrO2 nanocrystals

Abstract: We demonstrate single band upconversion spectra of Er3+ and Yb3+ codoped ZrO2 nanocrystals. Ratios of green to red emission in Er3+ doped ZrO2 and red to green emission in Er3+/Yb3+ codoped ZrO2 are 8 and 10, respectively. Rate equations for rare earth energy level populations are used to investigate the upconversion mechanisms on the basis of the upconversion intensity dependences of pump power. Excited state absorption and energy transfer are the dominant processes in Er3+ doped and Er3+/Yb3+ codoped ZrO2, respectively. [Copyright &y& Elsevier]