以Bi_2O_3-B_2O_3-ZnO为基质玻璃的原料组分,制备工艺采用传统的熔融冷却法,溶制温度950℃制备出基质玻璃。再通过低温共烧结法在基质玻璃中成功掺入Lu_(2.94-x)Y_XAl_5O_(12):0.06Ce(X=0~0.8)绿色荧光粉制备出绿色荧光玻璃。利用stc-4...以Bi_2O_3-B_2O_3-ZnO为基质玻璃的原料组分,制备工艺采用传统的熔融冷却法,溶制温度950℃制备出基质玻璃。再通过低温共烧结法在基质玻璃中成功掺入Lu_(2.94-x)Y_XAl_5O_(12):0.06Ce(X=0~0.8)绿色荧光粉制备出绿色荧光玻璃。利用stc-4000快速光谱仪和PMS-80可见光谱分析系统研究了不同电流下的LED器件光效、色温、色坐标的变化情况。结果表明,随着驱动电流从10 m A逐渐升高到30 m A,LED器件的测试光效大约下降16%,相关色温变化较小,色坐标未发生漂移。由于缺少红光成分,实验在绿色荧光玻璃上通过旋转涂覆一层红色荧光薄膜制备出高显色指数的暖白光LED,进一步推动绿色荧光玻璃在白光LED中的应用。展开更多
Advances in image quality in recent decades have made it necessary to develop new technologies for producing displays to meet remarkably stricter standards. The display market is governed mainly by liquid crystal disp...Advances in image quality in recent decades have made it necessary to develop new technologies for producing displays to meet remarkably stricter standards. The display market is governed mainly by liquid crystal display and light-emitting diode （LED） technology; however, it suffers from limitations that can be overcome by developing the next generation of electroluminescent displays. The introduction of colloidal quantum dots （QDs） as down-converters has enabled the production of displays with extremely high color purity and gamut. Therefore, colloidal nanocrystals are excellent candidates for the preparation of electroluminescent devices, which represent a straightforward approach to the development of unprecedented high-quality displays. We synthesized light-emitting QDs covering the entire visible spectrum with high fluorescence quantum yields and color purity, and produced high-brightness single-color LEDs with external quantum efficiencies of 0.39%, 1.04%, 2.10%, and 1.30% for red-, orange-, green-, and blue-emitting dots, respectively. Additional136 white LEDs were prepared by mixing QDs; they showed color temperatures of 5,300 K and color rendering indices exceeding 80%. Very importantly, we exhaustively characterized the LED performance, including the response time, stability, and evolution of the light characteristics, thus providing crucial information toward the development of high-quality electroluminescent displays.展开更多
We have synthesized Ca2Si5N8：Eu^2＋ phosphor through a solid-state reaction and investigated its structural and luminescent properties. Our Rietveld refinement of the crystal structure of Ca1.9Eu0.1Si5N8 reveals that...We have synthesized Ca2Si5N8：Eu^2＋ phosphor through a solid-state reaction and investigated its structural and luminescent properties. Our Rietveld refinement of the crystal structure of Ca1.9Eu0.1Si5N8 reveals that Eu atoms substituting for Ca atoms occupy two crystallographic positions. Between 10 K and 300 K, Ca2Si5N8：Eu^2＋ phosphor shows a broad red emission band centred at -1.97 eV-2.01 eV. The gravity centre of the excitation band is located at 3.0 eV 3.31 eV. The centroid shift of the 5d levels of Eu^2＋ is determined to be -1.17 eV, and the red-shift of the lowest absorption band to be - 0.54 eV due to the crystal field splitting. We have analysed the temperature dependence of PL by using a configuration coordinate model. The Huang-Rhys parameter S = 6.0, the phonon energy hv = 52 meV, and the Stokes shift △S = 0.57 eV are obtained. The emission intensity maximum occurring at -200 K can be explained by a trapping effect. Both photoluminescence （PL） emission intensity and decay time decrease with temperature increasing beyond 200 K due to the non-radiative process.展开更多
文摘以Bi_2O_3-B_2O_3-ZnO为基质玻璃的原料组分,制备工艺采用传统的熔融冷却法,溶制温度950℃制备出基质玻璃。再通过低温共烧结法在基质玻璃中成功掺入Lu_(2.94-x)Y_XAl_5O_(12):0.06Ce(X=0~0.8)绿色荧光粉制备出绿色荧光玻璃。利用stc-4000快速光谱仪和PMS-80可见光谱分析系统研究了不同电流下的LED器件光效、色温、色坐标的变化情况。结果表明,随着驱动电流从10 m A逐渐升高到30 m A,LED器件的测试光效大约下降16%,相关色温变化较小,色坐标未发生漂移。由于缺少红光成分,实验在绿色荧光玻璃上通过旋转涂覆一层红色荧光薄膜制备出高显色指数的暖白光LED,进一步推动绿色荧光玻璃在白光LED中的应用。
文摘Advances in image quality in recent decades have made it necessary to develop new technologies for producing displays to meet remarkably stricter standards. The display market is governed mainly by liquid crystal display and light-emitting diode （LED） technology; however, it suffers from limitations that can be overcome by developing the next generation of electroluminescent displays. The introduction of colloidal quantum dots （QDs） as down-converters has enabled the production of displays with extremely high color purity and gamut. Therefore, colloidal nanocrystals are excellent candidates for the preparation of electroluminescent devices, which represent a straightforward approach to the development of unprecedented high-quality displays. We synthesized light-emitting QDs covering the entire visible spectrum with high fluorescence quantum yields and color purity, and produced high-brightness single-color LEDs with external quantum efficiencies of 0.39%, 1.04%, 2.10%, and 1.30% for red-, orange-, green-, and blue-emitting dots, respectively. Additional136 white LEDs were prepared by mixing QDs; they showed color temperatures of 5,300 K and color rendering indices exceeding 80%. Very importantly, we exhaustively characterized the LED performance, including the response time, stability, and evolution of the light characteristics, thus providing crucial information toward the development of high-quality electroluminescent displays.
基金supported by the National Natural Science Foundation of China (Grant No 50672007)Program for the New Century Excellent Talents of China (Grant No NCET-06-0082)the National Basic Research Program of China (Grant No2007CB936202)
文摘We have synthesized Ca2Si5N8：Eu^2＋ phosphor through a solid-state reaction and investigated its structural and luminescent properties. Our Rietveld refinement of the crystal structure of Ca1.9Eu0.1Si5N8 reveals that Eu atoms substituting for Ca atoms occupy two crystallographic positions. Between 10 K and 300 K, Ca2Si5N8：Eu^2＋ phosphor shows a broad red emission band centred at -1.97 eV-2.01 eV. The gravity centre of the excitation band is located at 3.0 eV 3.31 eV. The centroid shift of the 5d levels of Eu^2＋ is determined to be -1.17 eV, and the red-shift of the lowest absorption band to be - 0.54 eV due to the crystal field splitting. We have analysed the temperature dependence of PL by using a configuration coordinate model. The Huang-Rhys parameter S = 6.0, the phonon energy hv = 52 meV, and the Stokes shift △S = 0.57 eV are obtained. The emission intensity maximum occurring at -200 K can be explained by a trapping effect. Both photoluminescence （PL） emission intensity and decay time decrease with temperature increasing beyond 200 K due to the non-radiative process.
