Researching Size, Shape, Phase And Luminescence Control Of Upconversion Nanocrystals

Near-infrared to visible upconversion NaLnF₄?Ln=Pr to Lu and Y?nanocrystals hold great promise for use in biological labeling and imaging due their intrinsic characteristics such as high chemical stability,non-blinking and sharp bandwidth luminescence,large Stokes shift as well as appropriate and abundant energy states for efficient energy transfer to achieve near-infrared to visible upconversion emission.However,there are still significant hurdles in the control of size,shape and phase of NaLnF₄ nanocrystals due to limited understanding of their growth behavior and growth mechanism.Here we describe an approach to facilely control the shape and phase of upconversion NaLnF₄ nanocrystals.Besides the optimization of general synthetic conditions such as organic surfactant and reaction temperature,we have developed an approach,in which a correlation between the ionic radius of lanthanide ions and the shape/phase of NaLn F4 nanocrystals is established,to precisely control the shape and phase of NaLnF₄ nanocrystals by finely tuning the mean ionic radius of lanthanide ions through lanthanide doping.The availability of such upconverting nanocrystals with controlled size,shape and phase provides a platform for applications ranging from biological imaging,biological sensing and three-dimensional displays.