Inorganic luminescent materials have been widely used as color converters for applications in lighting and displays [1-6].In recent years, laser-driven solid-state lighting based on phosphor-converted white laser diode (pc-WLD) technology, which is commonly fabricated with the combination of "blue LD+color converters", is rising for high-power lighting due to its super-high brightness, reliability and compactness [7,8].
In the development of static luminescent materials with remarkable optical-thermal performance and low cost, next-generation high-brightness laser lighting faces a key challenge. Herein, a unique composite architecture of Y3Al5O_(12):Ce^(3+) (YAG) phosphor-in-glass film coated on different heat-conducting substrates (PiGF@HCSs), i.e., PiGF@sapphire, PiGF@Al_(2)O_(3), PiGF@AlN, and PiGF@BN–AlN composites, was designed and prepared by a simple film printing and low-temperature sintering technology. The heat-conducting substrates significantly affect the luminescence saturation and phosphor conversion of PiGF@HCSs, allowing substrates with higher thermal conductivity (TC) to have a higher laser power density (LPD) and higher reflectivity to enable higher luminous efficacy (LE). As a consequence, PiGF@sapphire realizes a luminous flux (LF) of 2076 lm@12 W/mm^(2), which is higher than those of PiGF@Al_(2)O_(3) (1890 lm@15 W/mm^(2)) and PiGF@AlN (1915 lm@24 W/mm^(2)), whilePiGF@BN–AlN enables a maximum LF of 3058 lm@21 W/mm^(2). Furthermore, the LE of PiGF@BN–AlN reaches 194 lm/W, which is 1.6 times that of PiGF@AlN, while those of PiGF@sapphire and PiGF@Al_(2)O_(3) are 192 and 150 lm/W, respectively. The working temperature of PiGF@AlN is only 93.3℃ under LPD of 9 W/mm^(2), while those of PiGF@sapphire, PiGF@Al_(2)O_(3), and PiGF@BN–AlN increase to 193.8, 133.6, and 117℃, respectively. These findings provide guidance for commercial applications of PiGF@HCS converters in high-brightness laser lighting and displays.
Xin LiuMingxiang ChenJiuzhou ZhaoHongjin ZhangYang PengQing Wang
The work deals with cellulose paper filled with nanocellulose and SrAl2O4:Eu,Dy oxide phosphor.It was found that both nanocellulose and oxide improve the tensile strength of the composites obtained.The samples with the oxide demonstrate a long-lasting photoluminescence(PL)under sunlight and ultra-violet(UV)illumination.Room-temperature the PL spectra reveal a wide multicomponent band spreading over all the visible spectral regions.The short-wavelength part of the band is ascribed to the cellulose-related luminescence,while the long-wavelength PL component with maxima near 540 nm corresponds to the luminescence of the SrAl2O4:Eu,Dy phosphor.The dependency of the PL intensity on oxide concentration suggests the reabsorption of cellulose emission by the oxide and vice versa.The study of the dielectric properties of composite papers shows the presence of dielectric relaxations at low temperatures(T~−50℃).Similar cellulose materials to those studied can be considered as alternatives for artificial petroleum-based polymers.Low cost,eco-friendliness,biocompatibility,and the simplicity of recycling are among the main advantages of these materials.They are produced from the cellulose which is one of the most abundant renewable materials in nature.The data on the mechanical,dielectric,and optical properties indicate that the papers studied can be used in flexible lighting devices,WLEDs,coating,markers,labels,etc.
通过超薄层插入与掺杂相结合的方式,分别以激光染料DCM(4-(Dicyanomethylene)-2-methyl-6-(4-dimet-hyl-aminostyryl)-4H-pyran)、铱配合物Ir(ppy)3(tris(2-phenylpyridine)iridium)和联苯乙烯衍生物BCzVB(1,4-bis[2-(3-N-ethylcarbazoryl)vinyl]benzene)为红色、绿色和蓝色发射体,制备了磷光敏化荧光白色有机电致发光器件(OLED).通过改变DCM超薄层在CBP:Ir(ppy)3掺杂层中的插入位置实现了白色发光,最高外量子效率为2.5%(电流效率为5.1 cd/A),最高亮度为12400 cd/m^(2),且其中一种器件在1 mA/cm^(2)的电流密度下,国际照明委员会(Commission Internationale de L'Eclairage,CIE)坐标达到了理想白光平衡点(0.33,0.33).白光的获得归因于Ir(ppy)3适合的掺杂比例和DCM适合的插入位置,较好地均衡了红、绿、蓝三基色发光比例.结果表明,通过磷光敏化荧光实现三线态激子将部分能量传递给单线态激子,可望实现高效率白色有机电致发光器件,从而降低能耗并为促进OLED的应用提供更多空间.