Highly efficient white-light-emitting diodes fabricated with short-wavelength yellow oxynitride phosphors

We have already reported orangish yellow Ca–α-SiAlON:Eu2+ phosphors, and applied them to fabricate warm white light-emitting diodes (LEDs). In this letter, we report on greenish yellow Li–α-SiAlON:Eu2+ phosphors, and use them to create daylight when coupled to an InGaN blue LED chip (460nm). The newly discovered Li–α-SiAlON:Eu2+ phosphors emit at shorter wavelengths of 573–577nm under the 460nm excitation, and exhibit a smaller Stokes shift than Ca–α-SiAlON:Eu2+ does. By using this short-wavelength yellow oxynitride phosphor, bright daylight emissions from white LEDs can be generated. Thus, highly efficient white LEDs with tunable white light can be fabricated with α-SiAlON:Eu2+ phosphors, enabling them for a wider range of applications.