Glass Encapsulation Research Articles

Influences of additives on the fate of uranium during coal co-combustion process: The significant activation by CaCO3

High-efficiency extraction of uranium (U) is a key to determining the feasibility of radioactive hazards reducing and nuclear resources supplementing. So in this study, the influences of additives on U extraction during combustion were shown via Tessier extraction procedures and leaching tests. By co-firing U-rich coal with alkali metal-bearing, alkaline earth-bearing, and transition metal-bearing additives, the proportions of active U are decreasing, increasing, and ambiguous, respectively, among which CaCO3 displays the most remarkable improvement on U extraction. Thus, combining aqueous experiments with some characterizations (e.g., X-ray diffraction, scanning electron microscopy-energy dispersive spectroscopy), the fates of U during combustion with/without CaCO3 were comparatively studied as the roles of times (0–120 min), temperatures (450–1050 °C), and CaCO3 dosages (0–30%). Changes mainly include three points as co-firing time rising: 1) the oxidation of organics is suppressive in the CO2 atmosphere (owing to CaCO3 thermolysis), so U ions strongly associating with organics cannot turn into UOX at times ≤12 min; 2) the favorable captures of acidic phases, including UOx, by CaO promote the generation of uranate and its redistribution in alkaline eutectics; 3) although the former changes stabilize the existence of active U, iron oxides compete for the capture of UOX, contributing to its encapsulation in acid-insoluble glass. After co-firing with 20% CaCO3 and acid extraction, despite ~23.7% of U remaining in residue, it is promising to extract U by the method here, given a considerable improvement (~22.0%) on U extraction only under 5% CaCO3.

Comparative performance evaluation of different photovoltaic modules technologies under Kuwait harsh climatic conditions

In this work, performance analysis and comparison of eight photovoltaic (PV) technologies were carried out under the local harsh climate conditions of Kuwait. The test facility is elevated 3 metres​ above ground level on top of carports at the Kuwait Institute for Scientific Research (KISR), alongside the seashore. The test was carried out for two modules each of eight commercially available PV technologies, at total of 16 specimens. The eight technologies employed in this work are, Monocrystalline (m-Si), Polycrystalline (p-Si), Heterojunction (HIT), and thin film; Cadmium Telluride (CdTe), Copper Indium Gallium Diselenide (CIGS), and Amorphous Silicon (a-Si). The set of data analysed in this paper was systematically acquired during a period of 12 months. Special attention is given to the influence of temperature and dust on the performance of the PV modules. The results show that m-Si, p-Si and HIT modules performed better in high irradiance levels while decreasing rapidly at lower irradiance levels. However, in the case of the cylindrical CIGS module, good performance in low irradiance level was observed Two technologies in the study (a-Si and CdTe) performed significantly lower than the other technologies mainly due to capture losses. The performance analysis show that the HIT technology performed better than m-Si and p-Si technologies. Moreover the module’s geometry and construction materials had significant impact on module temperature, soiling loss, and subsequently module performance. Modules packaged with epoxy degraded faster than other modules with glass encapsulation under the same soiling rate due to dust fallout.

55‐3: Efficient, Low Haze Light Extraction for OLED Displays Using Micro‐Optic Patterns Imprinted on Glass

A novel design and application technique for light extraction in OLED displays are described, using micro‐optic patterns formed on the underside of an encapsulation glass. The design produces negligible haze and is fully compatible with the use of circular polarizers. A relative increase in brightness of 56% is demonstrated for a mobile phone display.

Omni-directional light capture in PERC solar cells enhanced by stamping hierarchical structured silicone encapsulation that mimics leaf epidermis.

Conventional crystalline silicon solar cell photovoltaic module technology requires much more development due to the challenges of efficiency loss and reliability problems such as browning damage. As an alternative to conventional ethylene-vinyl acetate (EVA)-glass encapsulation, silicone-based encapsulation is a promising innovation. Added to the many advantages of silicone based encapsulation for Si solar cells, here we present surface modification of silicone encapsulation with hierarchical structures inspired by leaf epidermis structures that improve light capture and hydrophobicity of the module surface using a simple, large-area silane and ozone treatment technique. The hierarchical structures comprise tens-of-micrometer-scale hills, valleys, and bump structures and sub-micrometer-scale wave patterns; the combination of these surface structures improved light transmission, light haze, and the wetting angle. These synergistic structures improve efficiency under vertical illumination compared to a bare cell, which is significant considering the efficiency loss in conventional EVA-glass encapsulation from those of bare cells. Furthermore, the enhancement increased the angle of incidence and improved the omni-directional performance so that electrical energy was generated more efficiently. We demonstrated that the modification of module surfaces by mimicking leaf epidermis structures yields considerable benefits, and further studies are expected to optimize this structure and identify the underlying principles for technological innovations based on silicone encapsulation.

Suppression of viewing angle dependence of TEOLED devices with internal nano-wrinkle structure

Abstract In order to suppress the viewing angle dependence of top emission organic emitting diodes (TEOLEDs) with strong microcavity effect, we introduced randomly distributed nano-wrinkle structure beneath highly reflective anode. By applying such nano-wrinkle pattern, viewing angle dependence and color shift could be improved compared with that without nano-structure [e.g. Δ (u’, v’): 0.077 → 0.025]. However, current efficiency reduced more than half. To compensate this problem, we additionally introduced index matching epoxy filler between encapsulation glass and TEOLED device. By this approach, current efficiency drop of device with nano-wrinkle structure could be improved. For example, the efficiency dropped by 7.7% when we filled the epoxy filler between capping layer and glass lid while, it decreased by 30.8% if we don't use epoxy filler. We found that index matching helps to extract more light confined inside TEOLED, so device performance degradation could be minimized. In addition, when we attached a circular polarizer film to these devices, depolarization was observed in most cases, but we were able to achieve a perfect black state from the devices with nano-wrinkle structure underneath reflective anode.

Coupled modelling approach for optimization of bifacial silicon heterojunction solar cells with multi-scale interface textures.

For advanced optical analysis and optimization of solar cell structures with multi-scale interface textures, we applied a coupled modelling approach (CMA), where we couple the rigorous coupled wave analysis method with ray tracing and transfer matrix method. Coupling of the methods enables accurate optical analysis of solar cells made of thin coherent and thick incoherent layers and includes combinations of nano- and micro-scale textures at various positions in the structure. The approach is experimentally validated on standalone single- and both-side textured crystalline silicon wafers, as well as on complete silicon heterojunction (Si HJ) solar cell structures. Using CMA, fully encapsulated bifacial Si HJ solar cells are optically simulated first by applying single- and both-side illumination, and the effects of introducing nano inverted pyramids and random micro-pyramids at front and/or rear interfaces are analyzed. Secondly, an external light management foil with a three-sided pyramidal micro-texture is applied in simulations to the front and/or rear encapsulation glass, and the related improvements are quantified. For the optimal combination of internal textures in the analyzed structure (random micro-pyramids at the front and nano inverted pyramids at the back) and the use of the light management foil on both sides of the device, a 5.6% gain in the short-circuit current is predicted, compared to the reference case with no light management foil and with random micro-pyramids applied to the front and rear internal interfaces.

Light management design in ultra-thin chalcopyrite photovoltaic devices by employing optical modelling

In ultra-thin chalcopyrite solar cells and photovoltaic modules, efficient light management is required to increase the photocurrent and to gain in conversion efficiency. In this work we employ optical modelling to investigate different optical approaches and quantify their potential improvements in the short-circuit current density of Cu(In, Ga)Se2 (CIGS) devices. For structures with an ultra-thin (500 nm) CIGS absorber, we study the improvements related to the introduction of (i) highly reflective metal back reflectors, (ii) internal nano-textures applied to the substrate and (iii) external micro-textures by using a light management foil. In the analysis we use CIGS devices in a PV module configuration, thus, solar cell structure including encapsulation and front glass. A thin Al2O3 layer was considered in the structure at the rear side of CIGS for passivation and diffusion barrier for metal reflectors. We show that not any individual aforementioned approach is sufficient to compensate for the short circuit drop related to ultra-thin absorber, but a combination of a highly reflective back contact and textures (internal or external) is needed to obtain and also exceed the short-circuit current density of a thick (1800 nm) CIGS absorber.

Constraints and Opportunities for Co2-Neutral Photovoltaics: In-Situ Perovskite Solar Cell Manufacturing Enables Reaching the Ultimate Carbon Footprint Limit of the Glass Substrate

Photovoltaics (PV) is on the way to become a global key energy technology. As PV is replacing fossil fuel based technology, it contributes to reduce the global CO2-emissions. However, it should be kept in mind that the fabrication of PV modules is connected with CO2 emission. To fulfil the Paris climate goals, the global PV industry needs to grow in such a way that it will have a significant share in global carbon emissions. Research-driven approaches to reduce the carbon footprint of PV have strong impact on this development. We identify the glass substrate and encapsulation as the ultimate lower boundary for carbon footprint for long-term stable grid connected PV technologies. By the in-situ concept for perovskite solar cells we introduce a holistic design approach guided by this lower limit for photovoltaic modules with a low carbon footprint of only 5% of current silicon PV. The feasibility of this idea is demonstrated by the fabrication of an efficient pre-encapsulated perovskite in-situ cell. The device shows record efficiencies of certified, stabilized 9.3 %. This is the highest reported efficiency of such solar cells with lowest carbon footprint.

Tuning solar absorption spectra via carbon quantum dots/VAE composite layer and efficiency enhancement for crystalline Si solar module

AbstractIn this work, fluorescent carbon quantum dots (CQDs) composite transparent film with blue emission was prepared via hydrothermal fabrication, mixing with vinyl acetate‐ethylene (VAE) emulsion, coated and cross‐linked on the glass in sequence. This CQD/VAE film has good sticking ability and compatibility of sealing ethylene‐vinyl acetate (EVA) material and works well as luminescent downshifting (LDS) materials. Based on these features, we did a set of optical characteristics analysis for CQD/VAE film and inserted a CQD/VAE film between glass and EVA encapsulation in a mini metal wrap through (MWT) solar module. This LDS could convert UV part of solar spectra, which are normally blocked by EVA, into the blue range and improve the light absorption by solar cell. Enhancement in the performance of solar modules was proved, especially the improvement of current of short circuit (Isc), external quantum efficiency (EQE) of the UV wavelength and solar module efficiency. This material provides the chance for prompt application, since it simply solves the dispersion problem of LDS material inside encapsulation and keeps the transparency of sealing polymer materials.

Heat Dissipation Properties of Thin‐Film Encapsulation by Insertion of a Metal Thin Film for Organic Light‐Emitting Diodes

Thin‐film encapsulation (TFE) technology composed of alternating inorganic/organic materials is a popular encapsulation technology for organic light‐emitting diodes (OLEDs), showing excellent heat‐transfer properties combined with a thick heat sink. TFE by inserting a metal thin film is proposed to improve the heat‐transfer property of an OLED without a separate thick heat sink. According to the presence of metal and its thickness and position, the heat dissipation effect of TFE is compared and optimized via finite element simulations. An obvious temperature‐reduction effect is observed by placing a metal thin film after each inorganic/organic unit compared with that found by placing a metal film after an inorganic/organic unit. Here, the TFE technology composed of alternating inorganic/organic/metal materials is defined as MET‐TFE. At a power density of 900 KW m−2, the highest internal temperatures of the devices were 70.14 °C (with glass encapsulation), 72.37 °C (with TFE) and 65.63 °C (with MET‐TFE). Furthermore, the simulated thermal analysis results show that the reduction rate of device temperature for a device with MET‐TFE is comparatively faster than those of devices with TFE and glass encapsulation when increasing the convective heat‐transfer coefficient. These results suggest that the MET‐TFE structure can effectively improve heat dissipation properties.

Encapsulating perovskite solar cells to withstand damp heat and thermal cycling

Glass and edge seal encapsulation of a perovskite solar cell to enable stability through damp heat and thermal cycling tests.

Highly-impermeable Al2O3/HfO2 moisture barrier films grown by low-temperature plasma-enhanced atomic layer deposition

Polymer substrates are essential components of flexible electronic applications such as OTFTs, OPVs, and OLEDs. However, high water vapor permeability of polymer films can significantly reduce the lifetime of flexible electronic devices. In this study, we examined the water vapor permeation barrier properties of Al2O3/HfO2 mixed oxide films on polymer substrates. Al2O3/HfO2 films deposited by plasma-enhanced atomic layer deposition were transparent, chemically stable in water and densely amorphous. At 60 °C and 90% relative humidity (RH) accelerated condition, 50-nm-thick Al2O3/HfO2 had water vapor transmission rate (WVTR) = 1.44 × 10−4 g m−2 d−1, whereas single layers of Al2O3 had WVTR = 3.26 × 10−4 g m−2 d−1 and of HfO2 had WVTR = 6.75 × 10−2 g m−2 d−1. At 25 °C and 40% RH, 50-nm-thick Al2O3/HfO2 film had WVTR = 2.63 × 10−6 g m−2 d−1, which is comparable to WVTR of conventional glass encapsulation.

Thermal stability, storage and release of proteins with tailored fit in silica

Biological substances based on proteins, including vaccines, antibodies, and enzymes, typically degrade at room temperature over time due to denaturation, as proteins unfold with loss of secondary and tertiary structure. Their storage and distribution therefore relies on a “cold chain” of continuous refrigeration; this is costly and not always effective, as any break in the chain leads to rapid loss of effectiveness and potency. Efforts have been made to make vaccines thermally stable using treatments including freeze-drying (lyophilisation), biomineralisation, and encapsulation in sugar glass and organic polymers. Here for the first time we show that proteins can be enclosed in a deposited silica “cage”, rendering them stable against denaturing thermal treatment and long-term ambient-temperature storage, and subsequently released into solution with their structure and function intact. This “ensilication” method produces a storable solid protein-loaded material without the need for desiccation or freeze-drying. Ensilication offers the prospect of a solution to the “cold chain” problem for biological materials, in particular for vaccines.

Suppression of viewing angle dependence of organic light emitting diodes by introduction of circular polarizer with nanoporous polymer film

To improve poor viewing angle characteristics of top emission organic light emitting diodes (TEOLEDs) without any serious pixel blur phenomena, we applied a circular polarizer (CP) film modified by nanoporous polymer film (NPF). From this approach, we could improve the color shift significantly (Δu'v’ in CIE 1976 with viewing angle, from 0.0165 to 0.0114), and expand angular light emission distribution of off-axis by applying CP with NPF. We found that black color shift was little associated with NPF position change although black color was slightly faded tint by applying NPF, as like plasma display panel(PDP)’s off condition. Very interestingly, we found that the reflectance was not changed seriously whether NPF exists between glass encapsulation and CP or not. Besides, we investigated the pixel blur level when we applied different condition in encapsulation thickness and morphology of diffusing films. As a result, we found that the pixel blur phenomena can be significantly suppressed by applying thin encapsulation and NPF type diffuser film.

Potential for photogenerated current for silicon based photovoltaic modules in the Atacama Desert

In order to evaluate module materials, the maximum theoretical value of the photo-generated current density, was calculated. The calculation was performed for four different solar cells, a standard p-type, passivated emitter and rear contact (PERC), bifacial cell and interdigitated back contact (IBC) considering a solar spectrum of Atacama Desert, the transmittance of several glass-encapsulant-glass structures and quantum efficiency. Regarding the solar spectrum in Atacama, an average air mass (AM) at noon for this location averaged 1.17 and the photovoltaic (PV) modules tilt angle was 20°. When studying the impact of using glass and encapsulants combined with a solar cell under the same solar spectrum, ethylene vinyl acetate (EVA) with low ultraviolet (UV) cutoff led to the higher current density values, up to 2% higher with the IBC solar cell compared to the other solar cells. The highest current gain, when studying the impact of the two spectra in the 300–1200nm wavelength range, was 7.4% for the IBC solar cell, obtained with a standard 3.2mm glass, a thermoplastic material (TM) as encapsulant. Considering the UV part of the spectrum, the current gain was maximized with a glass with an anti reflection coating (ARC) combined with the TM encapsulant for the IBC solar cell (25%). A quantification of losses due to reflection in the glass and absorption in the encapsulant revealed that the glass with ARC and the TM encapsulant different than EVA led to the lowest reflection and absorption losses. In this case, the reflection and absorption came down to 4.8% and 0.9%, respectively, contrasting with the 7% and 2.8% loss produced with the standard glass and EVA encapsulants.

Fabrication of bottom-emitting organic light-emitting diode panels interconnected with encapsulation substrate by Au[sbnd]Au flip-chip bonding and capillary-driven filling process

We present fabrication and testing of bottom-emitting organic light-emitting diode (OLED) panels based on flip-chip assembly and non-destructive scanning. In this method, the OLED and electric circuits are fabricated on separate substrates and interconnected by low temperature assembly to create a high-performance bottom-emitting OLED including other functions such as thin-film transistor (TFT) circuits. The low temperature assembly process consists of two steps. First, an OLED substrate and encapsulation glass with circuits are bonded at 100°C via AuAu bond. Encapsulation glass is utilized for the functional substrate with circuits. Next, the bonded panel is sealed by capillary underfill within and by applying and curing seal materials to the panel edge. The fabricated OLED was non-destructively evaluated by scanning acoustic microscopy (SAM). The SAM image shows all φ500μm Au bumps were bonded to Au pads, indicating that OLED and encapsulation substrates were assembled. Electroluminescence of the OLED was demonstrated by applying voltage. Stable current-luminance characteristics were obtained for the fabricated OLED with an operating voltage of 3.25V. The results indicate that the proposed fabrication is available for bottom-emitting OLED controlled by TFT circuits. In future, the assembly process can be widely applied to other flexible organic electronic devices with roll assembly by altering OLED or circuits with other devices because this is a simple pressure method with low temperature, achieving encapsulation at same time.

Amorphous–amorphous phase separation in hydrophobically-modified starch–sucrose blends I. Phase behavior and thermodynamic characterization

The glass transition of amorphous powders consisting of blends of octenyl-succinic anhydride (OSA) modified starch, and sucrose was studied as a function of blend composition and water content. Polarized light microscopy, differential scanning calorimetry (DSC) and water vapor sorption analysis were performed on four blends varying in their modified starch to sucrose ratio. The thermograms of the blends exhibit either a single glass transition event, characterized by a quite broad temperature range, or two glass transitions. This hints at a limited degree of phase separation into two amorphous phases within the blend matrix, most likely at the microscale. The results from dynamic water vapor sorption studies indicate that, in the phase-separated blends, the sucrose-rich phase constitutes the dispersed phase, while the continuous phase is formed by the phase rich in OSA starch. Our findings open up new ways to engineer glass encapsulation systems with composite structure, which can provide for a high level of protection of encapsulated bioactive compounds as well as defined release properties.

Improving the Performance of a Semitransparent BIPV by Using High-Reflectivity Heat Insulation Film

Currently, standard semitransparent photovoltaic (PV) modules can largely replace architectural glass installed in the windows, skylights, and facade of a building. Their main features are power generation and transparency, as well as possessing a heat insulating effect. Through heat insulation solar glass (HISG) encapsulation technology, this study improved the structure of a typical semitransparent PV module and explored the use of three types of high-reflectivity heat insulation films to form the HISG building-integrated photovoltaics (BIPV) systems. Subsequently, the authors analyzed the influence of HISG structures on the optical, thermal, and power generation performance of the original semitransparent PV module and the degree to which enhanced performance is possible. The experimental results indicated that the heat insulation performance and power generation of HISGs were both improved. Selecting an appropriate heat insulation film so that a larger amount of reflective solar radiation is absorbed by the back side of the HISG can yield greater enhancement of power generation. The numerical results conducted in this study also indicated that HISG BIPV system not only provides the passive energy needed for power loading in a building, but also decreases the energy consumption of the HVAC system in subtropical and temperate regions.

Role of solids composition on α-relaxation behavior, molecular structure and stability of spray-dried xanthones encapsulation systems around glass transition

Although the glass transition properties and encapsulation efficiency of various biopolymers have been documented, no attempts have been made to relate the α-relaxation behavior, molecular structure and stability of an encapsulation system above the glass transition. In this work, the efficiency of whey protein (W), maltodextrin (M) and their combination (MW) to encapsulate α-mangostin was assessed through the monitoring of the changes in the mechanical property and molecular structure around the glass transition using dynamic-mechanical analysis and Fourier transform infrared spectroscopy, respectively. A dramatic decrease in the storage modulus was observed in the non-encapsulation system (NE). Addition of W and M increased the temperature difference (Tstorage − Tα), resulting in a decrease in the α-mangostin degradation rate during storage. Carbonyl group (C–H) vibration of reducing sugars became smaller when W was added, while the spectra of the M and MW systems exhibited sharp peaks. This confirmed better encapsulation with W than with M.

The optical properties of solar cells before and after encapsulation

In this work we investigate how the optical properties of monocrystalline silicon and polycrystalline silicon wafers are affected by texturing techniques and encapsulation. For monocrystalline wafers, the KOH etching is better than acid etching while reactive ion etching (RIE) is proven to be preferred compared to acid etching for polycrystalline wafers. The differences in reflectance (R) between two textures are apparent before encapsulation, but when the textured wafers are encapsulated with glass especially antireflectance coated (ARC) glass, the difference can be reduced from about five percentage points to below a percentage point. More important, the optical losses caused by reflectance (R) losses and parasitic absorption losses (A) for four types of commercial monocrystalline and polycrystalline silicon module are quantified and compared. Analyses are carried out for eight configurations using a stratified model consisting of solar cell wafers as well as cover glass and ethylene vinyl acetate (EVA). The model is to first obtain the external reflectance (R) and transmittance (T) in each layer, and the spectrally parasitic absorption loss associated with the cover glass and EVA is calculated with the aid of R and T measurements, which allows us to do a complete optical loss analysis for the solar module. The results show that the KOH texture with ARC glass encapsulation may be better choice for monocrystalline wafers, which gives a 94.04% of effective light collected by silicon. The RIE technique with ARC glass is suitable for polycrystalline substrates with excellent light trapping of 94.14%. After all, reflectance from glass surface and silicon surface accounts for over 70% of total loss, while the absorption of glass and EVA accounts for the rest and less loss.