Guangshe Li and colleagues at the Fujian Institute of Research on the Structure of Matter, in China, have successfully prepared novel core/shell CaWO₄ micron spheres codoped with Na⁺ and Ln³⁺ (Ln³⁺ = Dy, Tb, Sm, Eu). The self-assembled particles showed a unique multicolour emission in the visible region when excited by a single-wavelength light source. These findings could simplify white light generation and relevant technologies. 

               

In conventional LED light sources, several phosphors are used, with different wavelength excitation sources, to produce white light. The development of these multicolour lights in single solids could eliminate the complications of tricolour mixing approaches and prompt the discovery of more functional nanosized materials with adjustable light colours in single-phase oxides. 

The motivation behind this work is that solid state white lighting has many promising applications and a huge market potential. This means that it is crucial to generate multicolour emissions in a single-phosphor by single-wavelength light excitation. The next challenge is to 'effectively control the energy transfer by the design and assembly of materials for high quantum efficiencies of white light generation,' said Li. 

Michael Brown