摘要
荧光粉的温度猝灭性质是影响白光LED的光效、光色参数和可靠性的关键因素之一。研究了不同激活剂浓度,不同元素掺杂的Y3-xCexAl5O12(YAG∶Ce3+)荧光粉在460nm光激发下的变温亮度和发射光谱。结果表明温度显著影响YAG∶Ce3+荧光粉的发光性能,随着温度的升高,发光强度下降,同时发射光谱红移。Ce含量为0.07(原子数分数)的YAG∶Ce3+荧光粉,150℃下亮度值约为室温时的89%,200℃时的发射光谱相对室温的红移了约10nm。Ce含量的改变对YAG∶Ce3+荧光粉的热猝灭性质影响较小。Lu的掺杂使YAG∶Ce3+荧光粉的发射波长蓝移,同时会显著改善荧光粉的热猝灭性能。Gd的掺杂使荧光粉的发射波长红移,同时也会导致热猝灭性能的劣化。
The cerium-doped yttrium aluminum garnet （YAG： Ce） phosphor is commonly used in white LED as the luminescence converter. The thermal quenching property of YAG： Ce^3＋ phosphor has important effects on the luminous efficiency, photo-chromic parameters and reliability of white LED at high temperature. In this paper, Y3-xCexAl5O12 and Y2.93-yCe0.07MyAl5O12（M =Lu, Gd） phosphors were prepared by the high temperature solid-state reaction method. The temperature-dependent photoluminescence properties of these phosphors were investigated under the excitation of 460 nm blue light. It is observed that the temperature has great influences on the photoluminescence properties of YAG： Ce^3＋ phosphors. With the temperature increasing, the relative brightness is decreased and the emission band shifts toward the red. For Y2.93 Al5O2： Ce0.07, the relative brightness at 150 ℃ is only 89% compared with that at the room temperature, and the emission band shifts toward the red for about 10 nm. The Ce^3＋ concentration has no obvious effect on the thermal quenching properties of YAG： Ce^3＋. For Lu-doped YAG： Ce^3＋ phosphors, the blue shift of the emission spectra is observed because of the introduction of Lu^3＋ ion which has a smaller ion radius than that of Y^3＋ ion. The emission peak shifts to the blue for about 15 nm as the concentration of Lu increases from 0 to 2.5. It is also noted that the Lu^3＋ substitution for Y^3＋ has an improvement on the thermal quenching property of YAG： Ce^3＋ phosphor. The relative brightness of Y2.93-yCe0.07 LuyAl5O12 phosphors with different y values retains above 94% at 150 ℃ compared with that at the room temperature. The relative brightness of LU2.93Al5O12：Ce0.07 / phosphor changes very little at elevated temperature, and falls only by 3% at 150℃ compared with its brightness at room temperature. The Gd substitution for Y^3＋ can shift the emission spectra of YAG： Ce^3＋ toward longer wavelength, at the expense of deteriorating the thermal quenching property. The red shift of the emission Gd increasing, the thermal quenching properties of Gd-doped YAG： Ce^3＋ phosphors are also worsened. At 150 ℃, the Y2.93-yGdyAl5O12：Ce0.07 phosphor with y =0.5 only can retain 78% of its luminance at room temperature, lower than that of undoped YAG： Ce^3＋ phosphor. The relative brightness of Y2.93-yGdyAl5O12： Ce0.07 phosphor with y =2.5 is below 90% when temperature is above 60 ℃ , and drop to 30% at 150 ℃.
出处
《发光学报》
EI
CAS
CSCD
北大核心
2008年第6期984-988,共5页
Chinese Journal of Luminescence
基金
教育部重大项目培育基金资助项目(707029)
