Understanding the Local and Electronic Structures toward Enhanced Thermal Stable Luminescence of CaAlSiN3:Eu2+

详细信息    查看全文

• 作者：Lei Chen ; Mi Fei ; Zhao Zhang ; Yang Jiang ; Shifu Chen ; Yongqi Dong ; Zhihu Sun ; Zhi Zhao ; Yibing Fu ; Jinhua He ; Can Li ; Zheng Jiang
• 刊名：Chemistry of Materials
• 出版年：2016
• 出版时间：August 9, 2016
• 年：2016
• 卷：28
• 期：15
• 页码：5505-5515
• 全文大小：918K
• 年卷期：0
• ISSN：1520-5002

文摘

It is a great challenge to maintain thermally stable luminescence of red phosphors in white light-emitting diodes (LEDs), because of the large Stokes shift. For the purpose of overcoming this challenge, this work elucidates the intrinsic mechanism of the thermal quenching luminescence of CaAlSiN₃:Eu²⁺. The empty 5d orbital of Eu²⁺ is partly filled with electrons upon Eu²⁺ increasing, as observed using XANES; and the exceptional expansion of the local Eu–N bond length, the ratio of which is far larger than the volume expansion of crystal lattice brought by doping Eu²⁺, is measured using EXAFS. The shift of Fermi level predicted with the first-principles calculations is confirmed by the valence band spectra. Therefore, the changeable distribution of electrons on the excited substates and then thermal delocalization to the conduction band are the intrinsic mechanisms of thermal quenching luminescence of CaAlSiN₃:Eu²⁺. The results provide a solid basis for exploring the methods to enhance the thermal stable luminescence of CaAlSiN₃:Eu²⁺.