Y_3Al_5O_(12):Ce^(3+),Cr^(3+)和Y_3 Al_5 O_(12):Ce^(3+),Pr^(3+),Cr^(3+)荧光粉体系中的能量传递

Energy Transfer in Y_3Al_5O_(12):Ce^(3+),Cr^(3+) and Y_3Al_5O_(12):Ce^(3+),Pr^(3+),Cr^(3+) Phosphors

通过在YAG:Ce^(3+)和YAG:Ce^(3+),Pr^(3+)荧光粉体系中分别掺入Cr^(3+)离子来提高蓝光管芯白光LED的显色指数。Cr^(3+)离子的加入,增加了红光发射,这归因于Cr^(3+)的~2E-~4A_2跃迁的零声子线和声子边带发光。Ce^(3+)→Cr^(3+)的能量传递是增强红光发射的重要方式,在YAG:Ce^(3+),Cr^(3+)体系中,由发射光谱得到的Cr^(3+)的红光与Ce^(3+)黄光发射强度的比值(I_2/I_1)与通过寿命测量得到的强度比很好符合。YAG:Ce^(3+),Pr^(3+),Cr^(3+)体系中,在只有Ce^(3+)离子被激发的状态下(λ_(ex)=340nm),3种能量传递过程同时存在:Ce^(3+)→Pr^(3+)、Ce^(3+)→Cr^(3+)和Pr^(3+)→Cr^(3+),进一步增加了红光比例。利用这两种荧光粉和460nm蓝光发射管芯封装得到的白光LED,在正向驱动电流为20mA时,LED的显色指数分别为80.4和81.4。

Triply doped Y_3Al_5O_（12）：Ce^（3＋）,Pr^（3＋）,Cr^（3＋）phosphors with Ce^（3＋）and Pr^（3＋）substituting for Y^（3＋）sites and Cr^（3＋）substituting for Al^（3＋）site are prepared by solid state reaction.A broad emission spectrum composed a yellow emission band from Ce^（3＋）,a light red emission line from Pr^（3＋）and a deep red emission line from Cr^（3＋）, which are generated through energy transfer among the dopant ions.The study of photoluminescence and fluorescence decay indicates that there exist energy transfers from Ce^（3＋）→Cr^（3＋）and Ce^（3＋）→Pr^（3＋）→Cr^（3＋）.The effect of energy transfer on relative intensities of the three emissions is analyzed.A white LED is fabricated using a blue LED chip coated with the triply doped phosphor and shows a color rendering index of 81.4 and 80.4, respectively.It is higher than that either using Ce^（3＋）and Cr^（3＋）doubly doped phosphor or Ce^（3＋）singly doped phosphors.