Modern intelligent electronic devices require electromagnetic interference (EMI) shielding composite films with outstanding shielding effectiveness and multifunctionality to adapt to increasingly complex application environments. In this work, inspired by the morphology of cocoa trees, SiO2 is conceived as the cocoa fruit and one-dimensional nanomaterial silver nanowires (AgNWs) as the branches. Utilizing the metal chelating properties of polydopamine (PDA), SiO2@PDA@AgNWs were formed and subsequently interwoven with cellulose nanofibers (CNFs) to create a nanocomposite film with a cocoa-tree-like structure, denoted as CNFs-AgNWs-SiO2@PDA (C-A-SP). Conductive AgNWs induce conductivity losses, while SiO2@PDA@AgNWs contribute to multiple scattering and interfacial polarization losses. Therefore, the C-A-SP nanocomposite film with a thickness of 59 mu m demonstrates an impressive EMI shielding effectiveness (EMI SE) of 76.91 dB and exhibits a specific SE (SSE/t) of 15304.88 dBcm2g-1. Meanwhile, the thermal conductivities of in-plane and out-plane reached 4.15 and 0.15 W/(mK), respectively. Additionally, the C-A-SP nanocomposite film also demonstrates an excellent strain-sensing capability. This study provides valuable insights for designing and fabricating lightweight, flexible, and multifunctional efficient EMI shielding composites.

The intelligent electronic devices have urgent demands for electromagnetic interference (EMI) shielding films with excellent heat dissipation capability. However, it is challenging to obtain excellent EMI shielding and thermal conductivity performances simultaneously. Herein, inspired by mille-feuille structure, the multifunctional EMI shielding films developed by a layer-by-layer self-assembly and hot-pressing strategy. The ingenious introduction of silver nanoparticles (AgNPs) with large specific surface area and highly conductive into the network formed by TEMPO-oxidized cellulose nanofibrils (TOCNFs) with large aspect ratio to form the TOCNFs/AgNPs. And the graphene nanoplates (GNPs) with high conductivity loss distributed alternately with TOCNFs/AgNPs to construct mille-feuille structure, which had highly efficient conductive network, complete thermally conduction pathway and rich heterogeneous interfaces. Consequently, the designed films presented high electrical conductivity of 8520 S/cm, superb EMI effectiveness (SE) of 98.05 dB, and excellent thermal conductivity of 18.82 W/(m·K). Furthermore, the films possessed outstanding Joule heating performances with low voltages, including high heating temperature (100 °C), fast response time (< 20 s), and impressive heating stability and reliability. Thus, such high-performance EMI shielding films with fascinating thermal conductivity and Joule heating performances have substantial application in flexible electronics, electromagnetic waves shielding and thermal management.

The lithium-sulfur battery (LSB) is a highly promising energy storage system with merits of exceptional theoretical specific capacity and energy density. However, challenges including insufficient sulfur conductivity, volume expansion, and the polysulfide shuttle effect result in rapid capacity decay and limited cycle life of the LSB, which significantly hinders its development. Inspired by the structure and forming process of paper, a fiber double network skeleton was constructed using flexible pulp fiber (PF) and highly conductive carbon fiber (CF). Following the principles of wet end chemistry in papermaking, MXene nanosheets with high adsorption and catalytic capacity for polysulfides were self-assembled on the surfaces of PF and CF to fabricate composite paper-based materials. The interwoven mesh of PF exhibited strong binding force and stable structure, providing support and protection for the CF interwoven mesh, resulting in a composite material with abundant porosity and excellent structural stability. Moreover, the CF interweaving network combined with an overlaid MXene interweaving network established an effective three-dimensional conductive pathway. When utilized as a self-supporting cathode in LSB, this composite paper-based material demonstrated outstanding cyclic stability. Under conditions of sulfur load at 2.3 mg·cm−2 and discharge at 0.2 C, the specific discharge capacity remained at 952 mAh·g−1 after 200 cycles with a capacity retention rate reaching 95.4

Achieving high shielding effectiveness in electromagnetic shielding materials relies heavily on high conductivity, yet simultaneously enhancing the absorption loss remains a persistent challenge. Consequently, the study successfully creates efficient electromagnetic shielding composite films with a unique grape-like bunch structure of hollow nanosilver (HCAF) through layer-by-layer assembly. The utilization of poly(dopamine) (PDA) to anchor nanosilver granules (AgNPs) onto cellulose nanofibers (CNF) results in the formation of CNF@PDA@AgNPs. Subsequently, a surface protection etching method is employed to etch the AgNPs, resulting in hollow nanosilver (H-AgNPs) and the generation of CNF@PDA@H-AgNPs. A composite film featuring a grape bunch structure is fabricated by interweaving high aspect ratio CNF with CNF@PDA@H-AgNPs. A substantial quantity of H-AgNPs creates an abundant interface, while the grape bunch structure establishes an efficient conductive network. That enables the composite film to exhibit excellent impedance matching, excellent conductivity loss, abundant polarization loss, and multiple reflection loss. Therefore, the conductivity of the composite film with a thickness of 148.8 mu m reaches 212660 S/m, with SE T , SE A , and SE R 89.56, 79.03, and 10.53 dB in the X band, significantly better than the 76.9, 55.55, and 21.41 dB of the solid AgNPs composite film. The composite film also exhibits remarkable thermal conductivity (The coefficients of in-plane and out-plane thermal conductivity are 4.61 and 0.17 W/(mK), respectively), mechanical properties, and strain sensing capabilities, making it significant potential for applications in flexible electronics and other related fields.

It is imperatively desired to design excellent electromagnetic interference (EMI) shielding and thermal management simultaneously. Herein, fabricating the multi-dimensional alternating layer nested (MALN) structure composite film, which consisted of the alternating multilayer structure constructed by silver nanowires (AgNWs)/cellulose nanofiber (CNF) layer and the graphene nanoplates (GNPs)/CNF layer, the dense conducting networks built by interweaving AgNWs in CNF networks, and the "mille-feuille" structure of GNPs and CNF. The heterogeneous layers of AgNWs/CNF layer and GNPs/CNF layer with significant conductivity differences, as well as the "mille-feuille" structure of CNF and GNPs, provide abundant macro/micro heterogeneous interface polarization losses and multiple reflection losses. Adjusting the addition of AgNWs or GNPs in different layers to form the conductivity gradient, endowing the "absorption-reflection-absorption" loss path and excellent conduction loss of film. Therefore, the MALN structure composite film with a thickness of 90 mu m exhibits an impressive EMI shielding efficiency (SE) of 98.95 dB and a specific SE (SSE/t) of 11606.14 dB/g center dot cm(-2), attribute to its excellent conduction loss, abundant macroscopic/microcosmic heterogeneous interfacial polarization losses, multiple reflection losses, and the absorption-reflection-absorption loss path. Meanwhile, the in-plane thermal conductivity (lambda(parallel to)) and out-plane thermal conductivity (lambda(perpendicular to)) achieve of 8.69 W/(m center dot k) and 0.16 W/ (m center dot k). Additionally, the obtained film also demonstrates exceptional joule heating, remarkable photothermal conversion, outstanding mechanical properties, and distinguished strain sensing capabilities, which exhibiting significant potential in wearable electronic devices.

Silicon-based anode materials are considered one of the highly promising anode materials due to their high theoretical energy density; however, problems such as volume effects and solid electrolyte interface film (SEI) instability limit the practical applications. Herein, silicon nanoparticles (SiNPs) are used as the nucleus and anatase titanium dioxide (TiO2) is used as the buffer layer to form a core-shell structure to adapt to the volume change of the silicon-based material and improve the overall interfacial stability of the electrode. In addition, silver nanowires (AgNWs) doping makes it possible to form a conductive network structure to improve the conductivity of the material. We used the core-shell structure SiNPs@TiO2/AgNWs composite as an anode material for high-efficiency Li-ion batteries. Compared with the pure SiNPs electrode, the SiNPs@TiO2/AgNWs electrode exhibits excellent electrochemical performance with a first discharge specific capacity of 3524.2 mAh·g−1 at a current density of 400 mA·g−1, which provides a new idea for the preparation of silicon-based anode materials for high-performance lithium-ion batteries.

Developing a sustainable, efficient and recyclable heterogeneous Fenton-like catalyst is important to wastewater treatment. Herein, well-dispersed MnO2 and Fe3O4 nanoparticles inlaid in chitosan beads (MnO2-Fe3O4/CH) was firstly fabricated and employed in the degradation of methylene blue (MB). The bead was prepared via a facile one-step method by dropwise addition of chitosan-metal salt solution into alkaline solution. Comparing with monometallic chitosan beads (MnO2/CH, Fe3O4/CH) and naked MnO2-Fe3O4, MnO2-Fe3O4/CH displayed significantly higher activity for MB degradation with the assistance of hydrogen peroxide (H2O2), finally removing 96.8% MB under the optimal conditions (50 mg L-1 MB, 4.0 g L-1 catalyst, 30 g L-1 H2O2, pH = 7, 60 min). Based on a series of characterizations, the large surface area (60.1 m2 g-1), well-developed porosity (0.3 cm3 g-1), and intensified electron transport of MnO2-Fe3O4/CH consequently enhanced the catalytic performance via a synergistic effect. Because the specific porous structure of MnO2-Fe3O4/CH facilitated the adsorption/diffusion of reactants and exposure of active sites. Meanwhile, the electron transfer from Mn3+ to Fe3+ accelerated the Fe3+/Fe2+ cycle, which favored the production of dominant reactive species hydroxyl radical for MB degradation. Besides, the magnetic beads could be easily collected from the solution and reused for five times with a negligible leaching.

This paper systematically investigates the luminous properties and thermal reliability of phosphor-in-glass (PiG)-based white light-emitting diodes (WLEDs). The PiG was prepared by introducing yellow YAG:Ce 3+ phosphor embedded with borosilicate glass through screen-printing and low-temperature sintering. The effects of sintering temperature, phosphor content, and phosphor layer thickness were studied, and then the optimized PiG was achieved. This PiG-based WLED module yields a luminous efficacy (LE) of 114 lm/W, a correlated color temperature of 5524 K, and a color rendering index of 69 at the driving current of 700 mA. Furthermore, after thermal aging test at 200 °C for 500 h, the photoluminescence intensity of PiG is only reduced by 4.3%, which is much lower than the conventional phosphor-in-silicone (PiS) of 26.2%. The LE losses of PiG-based and PiS-based WLED modules are 4.2% and 12.1% after thermal aging of 1000 h at 100 °C, respectively. The aging results show that the proposed PiG exhibits superior thermal stability characteristic, which promises the excellent thermal reliability for PiG-based WLEDs.

Silicone/phosphor composite is a functional material used in light-emitting diode packages. In this paper, Young’s modulus of silicone/phosphor composite is studied experimentally and investigated with a multi-sphere random unit cell model. Experimental samples of pure silicone and four groups of silicone/phosphor composites are prepared and subjected to tensile loading. Young’s moduli of the samples are calculated from tensile curves. The results indicate that composite modulus increases with increasing content of phosphor, and silicone matrix is stiffened by the phosphor particles. In the simulation part, unit cell model is utilized and serves as the statistical representation of the original composite. The employed three-dimensional random unit cell model consists of silicone matrix and randomly dispersed phosphor particles with various sizes. Modeling results from random unit cell model are compared with experimental results and theoretical predictions. It is found that, with increasing volume fractions of phosphor, random dispersion and size variation of phosphor have increasingly significant influence on homogenized Young's modulus of silicone/phosphor composite.

We proposed a novel method through introducing antireflective nanostructures on the surface of silica glass in the packaging process to enhance the light extraction efficiency (LEE) of deep-ultraviolet light-emitting diodes (DUV-LEDs). Optical simulations were conducted by rigorous coupled-waved analysis (RCWA) method, and the effect of geometry and dimension of the nanostructures on the transmittance improvement of the silica glass in a UV spectral range was investigated. By utilizing moth-eye nanostructures with feature sizes of 100 nm, the average reflectance of 0.44 % is achieved in the UV range. The nanostructures were fabricated by rapid thermal annealing and additional dry etching. The experimental results demonstrate that the LEE of DUV-LEDs packaged by the dual-side nanostructured glass increases by 8.6 % compared with that the flat glass packaged DUV-LEDs at driving current of 50 mA.

Phosphor-in-glass (PiG) patterned with micro-cone arrays, which can be fabricated by photolithography and inductively coupled plasma dry etching methods, is proposed to enhance light extraction efficiency (LEE) of white light-emitting diodes (LEDs) package. The effects of microstructure arrays on the LEE of LEDs are investigated by optical simulations and experiments. Optical performance of the LED package with microstructure patterned PiG is compared with that of flat PiG. Simulation results reveal that the truncated cone microstructure can increase the LEE by 12.3%. Experimental results also demonstrate that the enhancement of luminous efficiency of white LED reaches up to 9.7% with the inverted truncated cone microstructure.

A uniform, reproducible, and whole inorganic hermetic packaging technology using localized induction heating and its application to deep ultraviolet light-emitting diode (DUV-LED) packaging with glass cap have been proposed and demonstrated. By localized induction heating and inorganic packaging materials, the DUV-LED was rapidly packaged, which eliminates thermal damages during packaging process and avoids UV aging during its long-time service. At certain conditions, such as a treating period from 2 to 16 s and an output power from 1 to 6 kW, the bonding between ceramics and glass using Sn/Cu solder was achieved. The experimental measurement results indicate that localized induction heating packaging improves the electrical and optical characteristics of DUV-LED compared to global heating packaging.

To enhance the light efficiency of deep ultraviolet light-emitting diodes (DUV-LEDs), a novel method was proposed through introducing tailored nanostructures on the surfaces of silica glass in the packaging process. The nanostructures were fabricated by using self-assembled gold nanoparticles by rapid thermal annealing (RTA) and additional dry etching. The temperature and the dwelling time of RTA process were investigated to obtain the nanostructures with the optimized feature sizes of similar to 100 nm for the DUV application. By utilizing the dual-side nanostructures, the average transmittance of the glass increases from 90.1% to 97.2% in the UV range and is less dependent on the incidence angle. Meanwhile, the light efficiency of DUV-LEDs packaged by the dual-side nanostructured glass is increased by 8.6% compared with that of the flat glass at the current of 50 mA.

Volume fraction of phosphor in silicone has strong impact on microstructure and damage evolution of silicone/phosphor composite, which eventually affect the performance and reliability of light-emitting diodes (LEDs) packaging. In this paper, mechanical response of silicone/phosphor composite under exterior loading is investigated experimentally and numerically. Test samples of silicone with various amount of phosphor are prepared and subjected to tensile loading. Micro-scale morphology and fracture surfaces of samples are observed by scanning electron microscopy (SEM) after tensile tests. Interphase debonding can be identified on fracture surface and cracks are initiated around debonded phosphor particles. In order to provide micro-scale illustrations of the macro-scale behavior, a three dimensional multi-sphere random unit cell (RUC) model is introduced. Silicone matrix is modeled as hyperelastic solid and interphase region is modeled with cohesive law. Both experiment and simulation results demonstrate that, increasing the amount of rigid phosphor stiffens the silicone composite. On the other hand, increasing phosphor amount also shortens the average distance between rigid phosphor particles and intensifies strain localization in silicone matrix, which consequently results in interphase debonding and crack growth in the composite. This effect is regarded as the main mechanism that controls mechanical degradation of the silicone/phosphor composite.

To enhance light extraction efficiency and light quality of white light-emitting diodes (WLEDs), a randomly textured phosphor-in-glass (PiG), which can be fabricated by chemical wet-etching and screen-printing methods, is proposed. The performance of WLED with textured PiG is examined by experiments. Measurement results reveal that the luminous flux of WLED package with textured PiG increases by 4.6% compared that with flat PiG package. The increment is attributed to the fact that the roughened surface can reduce the total internal reflection (TIR) at the interface between air and PiG, leading to the enhancement of light extraction efficiency. Meanwhile, the textured PiG package reduces angular correlated color temperature (CCT) deviation from 1759K to 968K in the viewing angles of -75° to 75°, when the average CCT is about 5500K. With simplified process, low cost and superior optical properties, the textured PiG is expected to be a promising candidate for applications in solid-state lighting.

Light extraction of high power LED has always been an issue for the big refractive index contrast between LED chips and encapsulant. In this work, a new structure of encapsulant with gradient refractive index is designed and tested and its mechanism is studied. High refractive index TiO2-epoxy composite is fabricated by dispersing TiO2 nanoparticles into epoxy and its properties such as transmittance and RI are measured. Optimal structure with 2 layers is demonstrated to be more effective and have higher output power than conventional structure. Some experiments are designed to verify the performances of this new structure and show that the light power of GRIN encapsulant structure increases by 7.2% compare to conventional structure. Current-dependent light power is measured to further evaluate the performance of the GRIN encapsulant structure and shows that this structure exhibits excellent high-power performance.

ABSTRACT Silicone/phosphor composite is a functional material used in light emitting diode (LED) packages. In this article, effect of phosphor settling on mechanical properties and microstructure of phosphor/silicone composite is investigated experimentally and numerically. Test samples of silicones with various degrees of phosphor settling were prepared and uniaxial tensile tests were conducted. The results indicate that, for specific volume fraction of phosphor, phosphor sedimentation tends to reduce the strength and elongation of overall composite. And with increasing degree of sedimentation, the weakening effect becomes more significant. The fractographs of the test samples indicate that cracks initiate around the bottom area where phosphor particles settle. Numerical investigations, which were conducted by random unit cell model with graded particle distribution, demonstrate that strain localization and stress concentration are significant where phosphor particles concentrate. It can be concluded that, to reduce mechanical degradation, phosphor sedimentation should be minimized in silicone/phosphor composite for LED packages. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132 , 42006.

Because of the big refractive index difference between LED chip and encapsulant, a lot of photons generated in chip cannot escape out and finally convert to waste heat, which will rise the junction temperature and worsen the performances and reliability of LED devices. In this work, a glass film with gradient refractive index for LED packaging is proposed and its physical mechanism is studied. Glass powder is utilized to prepare light medium film and its RI can be adjusted by changing the mixture ratio of its component. Numerical and optical simulations are utilized to optimize the refractive index parameters and quantitative analysis. Structures with 2 to 3 optimal layers are demonstrated to be most effective and have the highest light extraction increase.

Angular color uniformity (ACU) is a key optical property of white light-emitting diodes (WLEDs) and high ACU is strongly demanded in illumination applications. In this paper, a multilayer phosphor-in-glass (PiG), which can be produced by the screen-printing method, is proposed to improve the ACU of LED packages. The screen-printing method provides a feasible scheme to produce multilayer, various-shaped PiG with a controllable pattern. Angular correlated color temperature (CCT) distributions of the LED packages with multilayer PiG are simulated numerically and measured experimentally. Optical performance of the LED package with optimized three-layer cone-shaped PiG is compared with that of packages with two-layer and one-layer PiG. The experimental measurements indicate that the deviation of angular CCT can be reduced from 761 to 171 K by cone-shaped PiG at average CCT of 6000 K. The results demonstrate that higher angular color uniformity can be achieved by LED packages with multilayer cone-shaped PiG.

Polymer based organic photovoltaic systems, which can be mass-produced by roll-to-roll printing technology, hold the promise for a cost-effective, lightweight and mechanical flexible solar energy conversion platform. Nevertheless, challenges still remain for large-scale applications of these flexible solar cells. One of the issues of great importance is the long-time reliability of solar cell module. It is demonstrated that organic solar cells can have wide range of applications, and therefore the surrounding temperature, humidity and load conditions vary. Rapidly changing thermo-mechanical loads often produce early failure of certain parts of the solar cell module, or even fracture of overall packaging which may result in the degradation of performance and life of solar cell. Therefore our work mainly focuses on the effect of elevated temperature on mechanical properties of materials in flexible solar cell panel. Temperature induced mechanical degradation and its effect on reliability of the packaging module are investigated. In our test, the samples made from flexible solar cell panel are stretched at a certain strain rate by test machine at 25°C, 75°C and 125°C, respectively. We find that Young's modulus of the materials decrease sharply with increasing temperature from the nominal stress-strain curve of materials and interfacial delamination occurs prior to material fracture at higher temperatures. Test results indicate that high temperature will not only reduce the mechanical stiffness of the materials in flexible solar cell, but also weaken the tensile strength of the material, which eventually undermined the reliability of solar cell packaging.