Mapping the glass forming region and making their phosphor-in-glass for application in W-LEDs packaging

The application of phosphor-in-glass (PiG) packaging material in white-light emitting diodes (W-LEDs) can improve the thermal stability and luminous efficacy of LED devices. In this work, a low melting point glass of TeO₂–ZnO–Na₂O–B₂O₃ (TZNB) was selected as glass matrix, and mixed with YAG: Ce³⁺ phosphor powders to obtain phosphor-in-tellurite glass (PiTG). In a significant advance, we mapped the glass forming region of TZNB for the first time. This high refractive index glass matrix with low melting temperature was achieved by optimizing the glass composition. The refractive index increased regularly from 1.61 to 2.03, when the dosage of TeO₂ increased from 15 to 75 mol%. Through Monte Carlo simulations and numerical calculations, the optimal structure of gradient refractive index (GRIN) was designed, which is consisted of TZNB-1 (n = 2.03), TZNB-4 (n = 1.79), TZNB-6 (n = 1.66), and glass substrate (n = 1.52). The PiTG with GRIN coating was fabricated by screen printing and low-temperature sintering, and the optimized sintering temperature is 575°C. Compared with the single refractive index (SRIN) coating, the luminous efficacy of PiTG with GRIN coating was enhanced from 9.51% to 23.12%. Therefore, this work provides a significant application in high-power W-LEDs.     

LED用高折射率有机硅封装材料的应用与研究进展

介绍了LED(发光二极管)用有机硅和EP(环氧树脂)封装材料的优势和劣势,并综述了近年来国内外LED用高折射率有机硅封装材料的研究现状及应用情况。最后展望了LED用高折射率有机硅封装材料的发展方向和发展前景。     

Compositional dependency of Cd-S-Se quantum dots within silicate glass on color conversion for a white LED

Quantum dot embedded glasses (QDEGs) were prepared by the conventional melt-quenching method to enhance its color conversion efficiency via optimizing the concentration of ZnS, ZnSe, and CdO within the silicate-based glass matrix. The QDEG, which contained 0.875 ZnS, 0.625 ZnSe, and 0.75 CdO (in mol%) and was heat treated at 500°C for 10 hours showed promising color conversion with an improved quantum yield of up to 25%. Color coordination of light-emitting diodes (LEDs) mounted with the QDEGs could be adjusted by tuning heat-treatment conditions and thickness control of QDEGs. The practical feasibility of the QDEG for a white LED is demonstrated with a reasonable glass thickness for LED packaging process. The formation of Cd-S-Se quantum dots within a glass matrix was identified by Raman and HR-TEM analyses. The effect of ZnSe and CdO on the formation of Cd-S-Se quantum dots within silicate glass is also discussed.     

Preparation and refractive index characterization of chalcogenide glasses with gradient refractive index

Infrared gradient refractive index (GRIN) lenses have great application value and potential in multispectral imaging systems. This study reports various chalcogenide axial GRIN glasses prepared using the hot-pressing diffusion method. It is worth noting that the S4–S60 GRIN sample has a difference in refractive index (RI) Δn of greater than 0.3 and a diffusion depth of about 5 mm, which is the deepest diffusion depth reported in chalcogenide glass to date. In addition, the linear portion in the profile of the GRIN sample has a RI difference of 0.15 and a thickness of 1.2 mm. The effects of the temperature, concentration difference, and diffusion time on the sample diffusion process are discussed. The dispersion properties of the GRIN samples were further calculated, providing a new option for correcting chromatic aberrations in optical systems. In addition, a method for the indirect nondestructive characterization of sample RI using the Raman intensity ratio is proposed, and the reliability of the method is verified by practical experiments, which is convenient for the subsequent measurement of the GRIN profile.     

New class of bioinspired lenses with a gradient refractive index

The recognition that eye lenses in nature often employ a gradient refractive index to enhance the focusing power and to correct aberrations has motivated us to construct a synthetic lens using the layered concept encountered in biological lenses. The result is a highly flexible technology for the fabrication of gradient‐refractive index lenses that is based on a method of polymer forced assembly. Polymeric nanolayered films with incremental differences in the refractive index are assembled according to a prescribed design and molded into the desired shape. The exceptional flexibility of the process lies in the wide range of lens shapes and index profiles that can be realized. A lens with any refractive index distribution can be achieved within the refractive index range of available coextrudable optical materials. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1834–1841, 2007     

Color conversion properties of various thick-film phosphor-in-glasses depending on structural design for white LEDs

Thick-film phosphor-in-glasses (PiGs) were fabricated via a screen-printing method with various phosphor layer structures, to compose a white light emitting diode (LED). Green (Lu₃Al₅O₁₂:Ce³⁺) and red (CaAlSiN₃:Eu²⁺) phosphors were mixed, layered, and patterned on a glass substrate. The chromaticity of each structured PiG was tuned to achieve a white LED by varying phosphor content and thickness. The emission spectra and the related various color conversion properties, including color coordinates, correlated color temperature (CCT), color rendering index (CRI), luminous efficacy (LE) and the color gamut of the mounted PiGs with different phosphor layer structures were examined and compared. Time-resolved photoluminescence (TRPL) measurements of the white LEDs with various phosphor layer structural designs were also obtained and compared. It was observed that spectral variation depended on the PiG layer structure. A proper PiG layer structural design was discussed for practical applications.     

Tunable chromaticity and enhanced luminous efficacy of white LEDs with phosphor-in-glass coating via multilayer screen-printing

The phosphor-in-glass (PiG) coating was fabricated via multilayer screen-printing and low-temperature sintering. The PiG coating consisted of Eu₂O₃-doped P₂O₅-ZnO-B₂O₃ (PZB) glass, Y₃Al₅O₁₂:Ce³⁺ (YAG:Ce) yellow phosphor, and CaAlSiN₃:Eu²⁺ (CASN:Eu) red phosphor. Eu₂O₃ and CASN:Eu were used to provide red emission for tunable chromaticity of white light-emitting diodes (LEDs), and surprisingly, the luminous efficacy was also enhanced. The impact of the variation in the B₂O₃ content on the PZB glass and the effect of Eu₂O₃, YAG: Ce, and CASN:Eu on the luminescent properties of the PiG coating were investigated. The glass matrix with 8 mol% B₂O₃ showed the lowest transition temperature and a suitable coefficient of thermal expansion. The spectra showed that the coating can be excited by blue light and produce yellow light and red light. The spatial distribution of the PiG coating was inspected by scanning electron microscopy, and it was observed that only a low erosion of phosphor by the glass matrix occurred. Furthermore, the white LEDs devices were constructed with the PiG coating on the blue LED chips. This method showed a decreased correlated colour temperature of 5137, a increased colour rendering index of 82.8 and an improvement in the luminous efficacy. The PiG coating for tunable chromaticity and enhanced luminous efficacy of white LEDs shows potential for application.     

Influence of lattice modifier on the nonlinear refractive index of tellurite glass

We studied the influence of different lattice modifiers (Nb₂O₅, Bi₂O_3, or TiO₂) on the nonlinear refractive index of a tellurite glass matrix by using the Z-scan technique. Based on the ability of the lattice modifiers to decrease the band-gap energy while simultaneously increasing the linear refractive index of the TeO₂-based glass, we investigated how these modifiers affect the nonlinear refractive indices. All studied glass presented high nonlinearities, and the addition of lattice modifiers made only a small contribution to increasing magnitude. These results could be explained through the observation of the band-gap energy reduction, which is related to the increase in the non-bridging oxygen content with the addition of the lattice modifier. The increase in the refractive index nonlinearity is explained by the optical basicity and the high electronic polarizability of the modifiers ions.     

Preparation of low refractive index fluorinated materials for antireflection coatings

Novel low refractive index fluorinated polymers were prepared from perfluoroalkylsilane and polyethoxysiloxane by a sol‐gel technique for antireflection applications. Perfluoroalkylsilane having low refractive index fluoroalkyl groups incorporate polyethoxysiloxane by condensation of their siloxane groups to improve the adhesion and hardness of the fluorinated polymers. Syntheses and characteristics of the fluorinated polymers were investigated by the studies of FTIR, GPC, UV–vis, ellipsometry, and mechanical tests. The experimental results reveal that the refractive index and hardness of the coating using the optimal fluorinated polymer were about 1.39 and 3H, respectively, which meet the requirements in practical applications. It was also found that the fluorinated polymer made from polyethoxysiloxane had a better hardness than that made from tetraethyl orthosilicate. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Fabrication of a gradient refractive index preform using laminar shear mixing

A gradient refractive index rod was successfully prepared by a new fabrication method using laminar shear mixing, and a graded index polymer optical fiber that satisfied IEEE1394b was obtained from the method. To fabricate the gradient refractive index rod, a liquid monomer mixture with a relatively low refractive index was placed in a prepared cylindrical glass reactor and a transparent polymer rod with a higher refractive index was introduced at the center of the reactor. The reactor and the polymer rod were then rotated concurrently with a small rotating speed difference to generate a Couette flow in the liquid phase. The centrifugal force generated by rotation and the polymer diffusion into the liquid monomer mixture developed a graded concentration profile in a radial direction. The Couette flow could reduce the concentration fluctuation in a tangential direction. In addition, the graded index profile could be controlled by the copolymer composition of the rod and its diameter. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1100–1104, 2005     

折光法在溶剂回收中的应用

报道了一种通过测试折光率来回收混合溶剂的方法。     

Preparation and performance of high refractive index silicone resin‐type materials for the packaging of light‐emitting diodes

A novel high refractive index and highly transparent silicone resin‐type material for the packaging of high‐power light‐emitting diodes (LEDs) is introduced, which was synthesized by hydrosilylation of vinyl end‐capped methylphenyl silicone resin and methylphenyl hydrosilicone oil catalyzed by Karstedt's catalyst. The vinyl end‐capped methylphenyl silicone resins were prepared by hydrolysis?polycondensation method from methylphenyl diethoxysilane (MePhSi(OEt)₂), phenyl triethoxysilane (PhSi(OEt)₃), and vinyl dimethylethoxy silane (Me₂ViSiOEt) in toluene/water mixture catalyzed by cation‐exchange resin. The vinyl end‐capped methylphenyl silicone resins were characterized by ¹H‐NMR and Fourier‐transform infrared. The performances of the cured silicone resin‐type materials for LED packaging have been examined in detail. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Specific refractive index increments of segmented polyurethanes

Specific refractive index increments ν of polyester-based segmented polyurethanes in N,N-dimethyl formamide have been determined, and the quotient dν/df_d has been evaluated (where f_d is the weight fraction of hard-segment units). The results are in good agreement with the values calculated from group contributions to the molar refraction, using the Vogel or the Gladstone–Dale equations. The values calculated with the Lorenz–Lorentz equation are too low. A potential explanation of this fact is proposed. The same methods have been applied to reported ν values for polyether-based polyurethanes. An explanation is proposed for differences in dν/df_d for polyester- and polyether-based polyurethanes. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1917–1923, 1998     

TiO2-BaO-SiO2系统高折射率玻璃微珠中ZnO含量的测定

本文阐述了一种新型的硅酸盐材料——高折射率玻璃微珠中ZnO含量的测定建立了一种化学分析方法,通过分离硅、钛、铝等主含量元素,用EDTAD滴定法滴定ZnO的含量,同时通过加标回收试验验证该方法的准确度和精密度。     

Structural relaxation dynamics of a silicate glass probed by refractive index and ionic conductivity

Relaxation occurs spontaneously in all glasses and is a fundamental step of important technological processes, such as annealing, crystal nucleation, and chemical strengthening by ion exchange. Despite extensive studies over the past decades, there are still conflicting results on whether the kinetics of structural relaxation depends on the analyzed property. Thus, in this study, we used a lithium disilicate glass as a model composition to determine the structural relaxation kinetics during physical aging experiments by measuring the time evolution of the refractive index and ionic conductivity down to 35 K below the initial fictive temperature. In all cases, variations in these properties were adequate to capture the structural changes throughout the aging experiments. At each temperature, the experimental relaxation data fit quite well with the classical stretched exponential relation. We also found that the relaxation process starts faster when probed by ionic conductivity than by refractive index; however, they show similar average relaxation times. These very small structural rearrangements are always the same, but ionic conductivity changes faster than refractive index at the beginning of the process. Our comprehensive results strongly indicate that relaxation dynamics is indeed dependent on the analyzed property.     

高折射率脂环型环氧有机硅预聚体的合成

以高含氢硅油(甲基氢硅油)为原料,在Lamoreaux催化剂作用下,先与N-烯丙基咔唑进行硅氢加成反应,再与4-乙烯基环氧环己烷反应,合成了折射率达1.577的脂环型环氧有机硅预聚体(Ep-Cz-SiO)。Ep-Cz-SiO的结构由¹H NMR和IR表征,并确定了分子中咔唑基团的含量。咔唑基团的引入显著提高了环氧有机硅预聚体的折射率。热重分析表明,所制备的带有咔唑基团的脂环族环氧有机硅预聚体的热稳定性高于含氢硅油原料。     

梯度光学功能玻璃研究进展

梯度折射率(GRIN)玻璃是指具有梯度折射率分布的光学功能玻璃,其在光学及光电学领域中具有广阔的应用前景.介绍了GRIN玻璃的形成原理及分类,综述了GRIN玻璃的制备技术及发展现状,讨论了它们各自存在的问题,提出了今后GRIN玻璃的研究方向.     

高折射率含硫环氧树脂PTETE的合成与表征

以苯硫酚、氯乙醇和环氧氯丙烷为原料,通过直接法合成高折射率苯硫基乙基-2,3环氧1丙硫醚（PTETE）环氧树脂。研究了原料配比、温度和氢氧化钠的用量等因素对产物产率的影响。得出最佳反应条件为：反应温度为0～10℃,环氧氯丙烷、MEPS与NaOH摩尔比为1．25：1：1,产率91．50％,产物的折射率1.6016。并通过FT-IR对合成的原料和产物进行表征。     

高折射率含硫环氧树脂的合成与表征

利用间接法以巯基乙醇和环氧氯丙烷 (ECH)为原料通过 3步反应得到 2 ,3 二 (2 ,3 环氧丙硫乙硫基 )丙基·2 ,3 环氧丙基硫醚型环氧树脂 (TGEBES) ,其折射率和环氧值分别达 1.5 85 0和 0 .5 3;在没有任何催化剂的条件下 ,按以三元硫醇 (BES)和ECH物质的量比为 1∶3.6、在温度为 0～ 5℃下反应 3～ 4h ,环氧化反应的产率达到84 .5 %。并利用红外光谱和核磁共振对含硫高折射率环氧树脂的结构进行了表征 ;利用高效液相色谱对TGEBES和BES的纯度进行了测定 ,结果表明TGEBES和BES纯度分别达 96 %和 97.7%以上。     

The relationship between refractive index and optical properties of absorbing nanoparticle

This article represents an analytical formulation for optical properties of absorbing metallic nanoparticles in visible region of electromagnetic spectrum based on Mie theory, in order to find a clear relationship between fundamental characteristics of nanoparticles with their spectral behavior and color coordinate in CIELAB color space. Calculations were performed on nanoparticles with various diameters (d = 50, 100, and 200 nm), as well as complex refractive index with different real (n = 1.5, 2.0, 2.5, and 3.0) and imaginary (k = 0.001 and 0.1) parts. Obtained results reveal that scattering phenomena in nanoparticles are strongly linked to the particle size parameter and complex index of refraction. The results indicate that the reflectance and lightness (L*) of nanoparticles increases as a result of increase in their size and real part of complex refractive index and decrease with increasing the imaginary part of complex refractive index. The CIELAB colorimetric system was used for analysis the color of nanoparticles. According to obtained results, all nanoparticles have greenish‐blue color, and undergo color change as a result of varying in their size and the complex refractive index. © 2015 Wiley Periodicals, Inc. Col Res Appl, 41, 477–483, 2016