Luminous efficacy and color rendering index of high power white LEDs packaged by using red phosphor

We packaged a series of high power white LEDs by covering the blue LED chips with yellow phosphor, red phosphor and the two phosphors mixed by appropriate mass ratio, respectively, and discussed the excitation and emission spectrum of yellow phosphor and red phosphor and the characteristics of the LEDs. We found that the luminous efficacy of the white LEDs covered with the two phosphors mixed by appropriate mass ratio was lower than that of the white LEDs covered with yellow phosphor, but the color rendering index was improved observably.     

高功率LED器件的热特性分析

GaN基白光LED不断向高功率、高性能和长寿命方向发展,GaN基白光LED的热性能成为在使用中的重要参数.采用瞬态热测量方式,对工作在不同的温度和驱动电流的GaN基发光二极管的热性能进行了研究.通过比较光、电特性发现LED芯片对器件热阻影响很小,但同时管芯附着层对LED器件的热特性起着非常重要的作用.此外,热电阻随着电流和环境温度的升高而增加,主要归因于管芯附着层声子或粒子的平均自由程减小.     

Luminous efficacy and color rendering index of high power white LEDs packaged by using red phosphor

We packaged a series of high power white LEDs by covering the blue LED chips with yellow phosphor, red phosphor and the two phosphors mixed by appropriate mass ratio,respectively,and discussed the excitation and emission spectrum of yellow phosphor and red phosphor and the characteristics of the LEDs.We found that the luminous efficacy of the white LEDs covered with the two phosphors mixed by appropriate mass ratio was lower than that of the white LEDs covered with yellow phosphor,but the color rendering index was improved observably.     

M3Gd（PO4）3：Tm^3＋（M=Mg，Ca，Sr，Ba）真空紫外发光特性

研究了M3Gd（PO4）3：Tm^3＋（M=Mg，Ca，Sr，Ba）样品的结构特性、发光特性。M3Gd（PO4）3：Tm^3＋属于立方晶系。基质掺入铥离子后其结构没有明显变化。M3Gd（PO4）3：Tm^3＋在166nm和210nm附近有强烈的吸收峰。位于166nm附近的强烈吸收峰归因于基质的强烈吸收，210nm附近的吸收峰则归因于Gd^3＋的^8S7/2-^6GJ的能级跃迁。在166nm真空紫外光激发下，样品在453nm及363nm处有较强的发射峰，发射主峰位于453nm。随着样品中阳离子的变化，M3Gd（PO4）3：Tm^3＋的激发峰发生强烈变化，从而导致其发射光谱有了较大变化。     

M3Gd(PO4)3:Tm3+(M=Mg,Ca,Sr,Ba)真空紫外发光特性

研究了M3Gd(PO4)3Tm3+(M=Sr,Ba,Ca,Mg)样品的结构特性、发光特性.M3Gd(PO4)3Tm3+属于立方晶系.基质掺入铥离子后其结构没有明显变化.M3Gd(PO4)3Tm3+在166 nm和210 nm附近有强烈的吸收峰.位于166 nm附近的强烈吸收峰归因于基质的强烈吸收,210 nm附近的吸收峰则归因于Gd3+的8S7/2-6GJ的能级跃迁.在166 nm真空紫外光激发下,样品在453 nm及363 nm处有较强的发射峰,发射主峰位于453 nm.随着样品中阳离子的变化,M3Gd(PO4)3Tm3+的激发峰发生强烈变化,从而导致其发射光谱有了较大变化.