Rigid Glass Research Articles

Implementation of various colors in Cu(In,Ga)Se2 thin-film solar cells by diffractive nanostructures

With the increasing use of building-integrated photovoltaic technology, it has become necessary for solar panels to blend in with their surroundings. Diffractive nanostructures can be used to reduce optical losses and create colorful solar cells. To make colors on Cu(In,Ga)Se2 (CIGS) thin-film solar cells, we fabricated diffractive nanostructures by using nanoscale imprinting and transfer lithography methods. And we investigated how the material types and pattern shapes of the nanostructures influence the optical properties of solar cells, such as the short-circuit current density (JSC), coordination of color appearance, and color quality. We used two types of pillars and grating nanostructures of SiO2 and TiO2 layers on CIGS thin-film solar cells to produce various colors. The SiO2 demonstrated an increase in JSC without significant loss of color quality compared to TiO2. By utilizing a hexagonally arrayed pillar pattern, colors are observed at various angles on an axis different from the incident light, unlike colors observed only at a single angle in the grating structure. The nanoimprinting lithography process allowed us to produce high-quality nanostructures on both rigid glass and flexible stainless-steel substrates.

All-Covalent Nuclease-Resistant and Hydrogel-Tethered DNA Hairpin Probes Map pN Cell Traction Forces.

Cells sense and respond to the physical properties of their environment through receptor-mediated signaling, a process known as mechanotransduction, which can modulate critical cellular functions such as proliferation, differentiation, and survival. At the molecular level, cell adhesion receptors, such as integrins, transmit piconewton (pN)-scale forces to the extracellular matrix, and the magnitude of the force plays a critical role in cell signaling. The most sensitive approach to measuring integrin forces involves DNA hairpin-based sensors, which are used to quantify and map forces in living cells. Despite the broad use of DNA hairpin sensors to study a variety of mechanotransduction processes, these sensors are typically anchored to rigid glass slides, which are orders of magnitude stiffer than the extracellular matrix and hence modulate native biological responses. Here, we have developed nuclease-resistant DNA hairpin probes that are all covalently tethered to PEG hydrogels to image cell traction forces on physiologically relevant substrate stiffness. Using HeLa cells as a model cell line, we show that the molecular forces transmitted by integrins are highly sensitive to the bulk modulus of the substrate, and cells cultured on the 6 and 13 kPa gels produced a greater number of hairpin unfolding events compared to the 2 kPa substrates. Tension signals are spatially colocalized with pY118-paxillin, confirming focal adhesion-mediated probe opening. Additionally, we found that integrin forces are greater than 5.8 pN but less than 19 pN on 13 kPa gels. This work provides a general strategy to integrate molecular tension probes into hydrogels, which can better mimic in vivo mechanotransduction.

Light‐Induced Thin‐Film Transfer Processes Based on Phase Transition of GeSbTe and ITO Sacrificial Layers

AbstractIn the upcoming ubiquitous era, wearable/flexible electronics are spotlighted to get various types of numerous information in real time. Several researchers have investigated flexible materials, and developed diverse thin‐film transfer methods. However, there are some limitations of the intrinsic material unstabilities, and low production yield. Here, light‐induced thin‐film transfer methods are reported by using new transfer mechanism of phase transition in sacrificial materials. Lift‐off conditions with high‐energy laser are delicately optimized by theoretical calculations and experiments to minimize mechanical/thermal damages of the upper thin‐film devices. The selected sacrificial materials of GeSbTe (GST) and indium tin oxide (ITO) with the 300 nm thickness are delaminated from a transparent and rigid glass substrate by irradiating the excimer laser to the surface of the sacrificial layer. The laser‐based exfoliation mechanism of GST and ITO films are comprehended by various material surface analyses. Eventually, flexible oxide thin‐film transistors (TFTs) are successfully demonstrated through light‐induced exfoliation process, showing the usability of the developed transfer technique to future practical applications.

Substrate Dependence of CdSe/ZnS Quantum-Dot Light-Emitting Diodes: A Comparative Study between Rigid Glass and Flexible Plastic Substrates.

The purpose of this study was to investigate the effect of substrate characteristics on the performance of quantum-dot light-emitting diodes (QLEDs) with the aim of developing high-performance flexible QLEDs. Specifically, we compared QLEDs made with a flexible polyethylene naphthalate (PEN) substrate to those made with a rigid glass substrate, using the same materials and structure except for the substrates. Our findings indicate that the PEN QLED had a 3.3 nm wider full width at half maximum and a 6 nm redshifted spectrum in comparison to the glass QLED. Additionally, the PEN QLED exhibited a 6% higher current efficiency, a flatter current efficiency curve, and a 2.25-V lower turn-on voltage, indicating superior overall characteristics. We attribute the spectral difference to the optical properties of the PEN substrate, such as light transmittance and refractive index. Our study also revealed that the electro-optical properties of the QLEDs were consistent with the electron-only device and transient electroluminescence results, which suggests that the improved charge injection properties of the PEN QLED were responsible. Overall, our study provides valuable insights into the relationship between substrate characteristics and QLED performance, which can be used to develop high-performance QLEDs.

Highly efficient CsPbBr3@glass@polyurethane composite film as flexible liquid crystal display backlight.

Inorganic lead halide perovskite quantum dots (CsPbX3 QDs (X = Cl, Br, or I)) have attracted more and more attention due to their high absorption coefficient, narrow emission band, high quantum efficiency, and tunable emission wavelength. However, CsPbX3 QDs are decomposed when exposed to bright light, heat, moisture, etc., which leads to severe luminous attenuation and limits their commercial application. In this paper, CsPbBr3@glass materials were successfully synthesized by a one-step self-crystallization method, including melting, quenching and heat treatment processes. The stability of CsPbBr3 QDs was improved by embedding CsPbBr3 QDs into zinc-borosilicate glass. Then, the CsPbBr3@glass was combined with polyurethane (PU) to form a flexible composite luminescent film CsPbBr3@glass@PU. This strategy enables the transformation of rigid perovskite quantum dot glass into flexible luminescent film materials and further improves the photoluminescence quantum yield (PLQY) from 50.5% to 70.2%. The flexible film has good tensile properties, and its length can be strained 5 times as long as the original length. Finally, a white LED was encapsulated by combining CsPbBr3@glass@PU film and red phosphor K2SiF6:Mn4+ with a blue LED chip. The good performance of the obtained CsPbBr3@glass@PU film indicates that it has potential application in flexible liquid crystal displays (LCDs) as a backlight source.

A transparent room-temperature ferromagnetic semiconductor on glass: anatase Co-doped TiO2 oriented thin films with improved electrical conduction

(101)-Oriented anatase Ti0.95Co0.05O2−δ thin films were grown on rigid and flexible glass substrates by using TiO2 seed layers. The thin films exhibited ferromagnetic semiconducting properties comparable to those of epitaxial thin films.

Well-Dispersive Polypyrrole and MoSe2 Embedded in Multiwalled Carbon Nanotube@Reduced Graphene Oxide Nanoribbon Electrocatalysts as the Efficient Counter Electrodes in Rigid and Plastic Dye-Sensitized Solar Cells

In this study, a core–shell structured multiwall carbon nanotube@reduced graphene oxide nanoribbon (MWCNT@rGNR) was prepared by the facile unzipping of MWCNTs with mild conditions to synthesize the composites of the MWCNT@rGNR and polypyrrole (PPy) or MoSe2, which were used as the electrocatalysts for the counter electrodes (CEs) in dye-sensitized solar cells (DSSCs). The transmission electron microscopy image of the MWCNT@rGNR showed a graphene sheet structure found on both sides of the MWCNTs, indicating a central core of the MWCNTs and its shell of the rGNR. The obtained MWCNT@rGNR functionalized with PPy or MoSe2 was envisaged to have the advantages of both component, that are the unique electronic structure of the MWCNT@rGNR and the synergistic effects of conductive PPy or electrocatalytically active MoSe2, respectively. The DSSCs with PPy/MWCNT@rGNR0.3 and MoSe2/MWCNT@rGNR0.3 showed comparable efficiency (photoelectric conversion efficiency, PCE = 7.48 and 8.34%, respectively), short-circuit current (Isc = 17.97 and 17.11 mA cm–2, respectively), and open-circuit voltage (Voc = 0.80 and 0.84 V, respectively) without any loss of the fill factor (FF = 0.52 and 0.58, respectively) as compared to the cell fabricated using a standard Pt electrode. The PCE of a standard Pt CE was 7.70% with an Isc of 16.09 mA cm–2, Voc of 0.76 V, and FF of 0.63. According to the results of the electrochemical measurements, composites with PPy or MoSe2 showed better electrocatalytic activity, higher redox-active surface area, and extremely large heterogeneous electron transfer rate constant. The plastic devices assembled with the PPy/MWCNT@rGNR0.3 and MoSe2/MWCNT@rGNR0.3 coated on a flexible plastic substrate (indium tin oxide-coated polyethylene naphthalate; ITO/PEN)exhibited impressive PCEs of 4.61 and 5.25%, respectively, comparable to those coated on the rigid fluorine-doped tin oxide glass substrate. This work presented a facile low-temperature method to fabricate high-performance MWCNT@rGNR composite-based CEs to make them applicable to large-scale plastic DSSCs.

OLEDs on planarized light outcoupling-enhancing structures in plastic

Light extraction from OLEDs remains a challenge. While consumer demand for OLEDs in display technology continues to grow as prices decline, commercial use of OLEDs in solid state lighting (SSL) applications is lagging due to low light extraction, which results in low efficiency. Previous studies have been directed toward increasing the light extraction factor η out , but cost-effective approaches that will enable high throughput and potential upscaling, as well as elucidation of the extraction process, are still lagging. One promising approach is the use of buried light extraction enhancing patterns that are planarized with a high refractive index (RI) layer. When adding substrate mode extracting means, the highest external quantum efficiencies (EQEs) were achieved using a complex approach of planarized vacuum nano holes. Here we present η out -enhancing planarized extraction structures (PES) in plastic. While plastic substrates currently present long-term stability issues and other drawbacks, as we show, they provide a tool for simple, inexpensive, and rapid generation of various enhancing structures that importantly can be transferred to the preferred rigid and flexible glass substrates. Moreover, plastic substrates are attractive for biomedical applications. The successful structures we present are easily scalable periodic corrugations, e.g., with pitch a ∼4.25 μm and pitch/depth ratio a/h ∼ 2.4 planarized by a layer of RI ∼1.9, resulting in maximal EQEs exceeding 60% for a green OLED and 48.5% for a white OLED. Comparable increased EQEs were achieved for structures with a ∼15 and 16 μm, and a/h ∼2.1 and 4, respectively. Enhanced extraction was also observed with a very simply fabricated quasiperiodic nanohole array, and surprisingly, with a random shallow design. The latter is at variance with simulations based on diffraction only. Results are discussed in terms of a , h , and structural parameters together with scattering matrix simulations to assess the effect of various PES parameters and the nanoparticle-embedded planarizing layer on η out . The experiments and simulations indicate contributions of diffraction, reflection, and scattering to EQE enhancement. • Light outcoupling-enhancing planarized extraction structures (PES) in plastic. • A tool for simple, inexpensive, & rapid generation of various enhancing structures. • Useful PES: periodic patterns, quasiperiodic nanohole array, random shallow design. • EQEs achieved: 61% - green OLED; 48.5% - white OLED. • Experiment & theory: enhanced EQEs due to diffractive & diffuse light scattering.

Electrochemical Bonding of Hydrogels at Rigid Surfaces.

Flexible hydrogels can be chemically/physically bonded on soft surfaces. However, there is a lack of a facile method to build strong interfacial adhesion between hydrogel and various rigid surfaces. Herein, an electrochemical bonding protocol, which improves the interfacial adhesion energy of hydrogel from initial 8 to 3480 J m-2 , ≈435 times enhancement at rigid glass surface, superior to the most of traditional methods, is proposed. A series of electrochemical bonding models to analyze the bonding mechanism, is demonstrated. The results indicate that the electrode reactions generate Fe3+ ions at the anode and OH- ions at the cathode, which migrate and react to form nanoparticles of Fe(OH)3 . These nanoparticles form hump-like physical structures at the interface and work as mechanical-bonding sites, enabling the strong interfacial adhesion. Upon applying acidic solution to decompose the nanoparticles, the strong adhesion can be weakened to easily remove hydrogel from the bonded surface. The electrochemically-bonded hydrogel can maintain its adhesion in water, which enables the electrochemical bonding of hydrogels for repairing various damaged surfaces such as plastic water tubes/bags, indicating promising potential for adhesive engineering applications.

Microsurgical Manipulations to Isolate Collectively Migrating Mesendoderm.

Mesendoderm mantle closure completes the gastrulation movements of the <i>Xenopus laevis</i> embryo and provides an unparalleled opportunity to study collective cell behaviors within a mesenchymal tissue. Free-edge sheet-like collective movements of these tissues contrast with movements of epithelial tissues in that mesendodermal cells are not constrained by tight junctions or adherens junctions, yet migrate in a coherent and persistent mode over several hours. Mesendoderm cells are the largest motile cells in the <i>Xenopus</i> embryo and complete a 500-µm migratory path. When mesendoderm is cultured on rigid glass substrates, these cells can exceed 100 µm in length and show a highly persistent leading lamellipodia that can exceed 20 µm from tip to base. These large collectively migrating cells provide a unique imaging opportunity to visualize polarized adhesive and cytoskeletal structures with high-numerical-aperture objectives. Mesendodermal cells in the early embryo originate from around the entirety of the marginal zone and may also be distinguished by their source along the animal-vegetal axis. Here we use the term mesendoderm but note alternative terms for these cells can include head mesoderm, endomesoderm, and prechordal mesoderm. This protocol summarizes microsurgical preparation of mesendoderm tissue explants and "windowed" embryos. Skills needed to dissect fragments of the mesendoderm mantle are marginally greater than those needed to isolate animal cap ectoderm and can be mastered within 2 weeks; skills needed to isolate the mesendoderm "donut" or "ring" or to prepare windowed embryos are significantly greater and may require several additional weeks of training.

Analysis of a Costly Fiberglass-Polyester Air Filter Fire

In September 2020, a fire at a liquefied natural gas (LNG) plant in the Arctic areas of Norway received national attention. In an unengaged air intake, the heat exchanger designed to prevent ice damage during production mode, was supplied hot oil at 260 °C. In sunny weather, calm conditions, and 14 °C ambient temperature, overheating of the unengaged air intake filters (85% glass fiber and 15% polyester) was identified as a possible cause of ignition. Laboratory heating tests showed that the filter materials could, due to the rigid glass fibers carrying the polymers, glow like smoldering materials. Thus, self-heating as observed for cellulose-based materials was a possible ignition mechanism. Small-scale testing (10 cm × 10 cm and 8 cm stacked height) revealed that used filters with collected biomass, i.e., mainly pterygota, tended to self-heat at 20 °C lower temperatures than virgin filters. Used filter cassettes (60 cm by 60 cm and 50 cm bag depth) caused significant self-heating at 150 °C. At 160 °C, the self-heating took several hours before increased smoke production and sudden transition to flaming combustion. Since the engaged heat exchanger on a calm sunny day of ambient temperature 14 °C would result in temperatures in excess of 160 °C in an unengaged air intake, self-heating and transition to flaming combustion was identified as the most likely cause of the fire. Flames from the burning polymer filters resulted in heat exchanger collapse and subsequent hot oil release, significantly increasing the intensity and duration of the fire. Due to firewater damages, the plant was out of operation for more than 1.5 years. Better sharing of lessons learned may help prevent similar incidents in the future.

19.1: Invited Paper: Electrochromic Display Based on Semiconducting Polymer

19.1: <i>Invited Paper:</i> Electrochromic Display Based on Semiconducting Polymer

Hydrogen-Induced Aggregation of Au@Pd Nanoparticles for Eye-Readable Plasmonic Hydrogen Sensors.

Plasmonic materials provide a promising platform for optical hydrogen detection, but their sensitivities remain limited. Herein, a new type of eye-readable H2 sensor based on Au@Pd core-shell nanoparticle arrays (NAs) is reported. After exposed to 2% H2, Au@Pd (16/2) NAs demonstrate a dramatic decrease in the optical extinction intensity, along with an obvious color change from turquoise to gray. Experimental results and theoretical calculations prove that the huge optical change resulted from the H2-induced aggregation of Au@Pd nanoparticles (NPs), which remarkably alters the plasmon coupling effect between NPs. Moreover, we optimize the sensing behavior from two aspects. The first is selecting appropriate substrates (either rigid glass substrate or flexible polyethylene terephthalate substrate) to offer moderate adhesion force to NAs, ensuring an efficient aggregation of Au@Pd NPs upon H2 exposure. The second is adjusting the Pd shell thickness to control the extent of NP aggregation and thus the detection range of the as-prepared sensors. This work highlights the advantage of designing eye-readable plasmonic H2 sensors from the aspect of tuning the interparticle plasmonic coupling in NP assemblies. Au@Pd NAs presented here have several advantages in terms of simple fabrication method, eye-readability in air background at room temperature, tunable detection range, and high cost-effectiveness.

A Flexible Chamber for Time-Lapse Live-Cell Imaging with Stimulated Raman Scattering Microscopy.

Stimulated Raman scattering (SRS) microscopy is a label-free chemical imaging technology. Live-cell imaging with SRS has been demonstrated for many biological and biomedical applications. However, long-term time-lapse SRS imaging of live cells has not been widely adopted. SRS microscopy often uses a high numerical aperture (NA) water-immersion objective and a high NA oil-immersion condenser to achieve high-resolution imaging. In this case, the gap between the objective and the condenser is only a few millimeters. Therefore, most commercial stage-top environmental chambers cannot be used for SRS imaging because of their large thickness with a rigid glass cover. This paper describes the design and fabrication of a flexible chamber that can be used for time-lapse live-cell imaging with transmitted SRS signal detection on an upright microscope frame. The flexibility of the chamber is achieved by using a soft material - a thin natural rubber film. The new enclosure and chamber design can be easily added to an existing SRS imaging setup. The testing and preliminary results demonstrate that the flexible chamber system enables stable, long-term, time-lapse SRS imaging of live cells, which can be used for various bioimaging applications in the future.

Fabrication of Low-Cost Resistance Temperature Detectors and Micro-Heaters by Electrohydrodynamic Printing.

EHD printing is an advanced deposition technology that is commonly utilized for the direct manufacture of electrical devices. In this study, meander-type resistive electrodes consisting of silver nanoparticles were printed directly on rigid glass and flexible polyethylene terephthalate (PET) substrates. High-resolution patterns of ≈50 µm linewidth were successfully printed on untreated surfaces utilizing a bigger nozzle of 100 µm inner diameter after improving the experimental settings. The manufactured electrodes were evaluated and used as Resistance Temperature Detectors (RTDs) and micro-heaters in a systematic manner. The temperature sensors performed well, with a Temperature Coefficient of Resistivity (TCRs) of 11.5 and 13.3 , for glass and PET substrates, respectively, throughout a wide temperature range of 100 °C and 90 °C. Furthermore, the RTDs had a quick response and recovery time, as well as minimal hysteresis. The electrodes’ measured sensitivities as micro-heaters were 3.3 °C/V for glass and 6.8 °C/V for PET substrates, respectively. The RTDs were utilized for signal conditioning in a Wheatstone bridge circuit with a self-heating temperature of less than 1 °C as a practical demonstration. The micro-heaters have a lot of potential in the field of soft wearable electronics for biomedical applications, while the extremely sensitive RTDs have a lot of potential in industrial situations for temperature monitoring.

An area-variant type MEMS capacitive sensor based on a novel bionic swallow structure for high sensitive nano-indentation measurement

In this paper, a high sensitive area-variant type MEMS capacitive sensor was proposed for nano-indentation measurement. The proposed bionic swallow structure processed a high mechanical sensitivity without influences from the load coupling effect. Six comb arrays were optimized and integrated into the proposed sensor with a novel comb sensing configuration for eliminating electrostatic interferences resulting from multiple combs and maintaining compact chip size. Based on the proposed micro-machined process, comb arrays have been fabricated with great consistency, which exhibited a static differential output of 0.0554 pF. The fabricated sensor has been characterized with rigid glass cube and AFM cantilevers, and the measured force sensitivity can reach 98.54 aF/nN for a larger measurement range of 142 µN with a linearity of 0.9996. The fabricated sensor also exhibited a high resolution of 0.9819 nN, indicating its great feasibility in nano-indentation measurement at the sub-nano-Newton level.

Fluorescence and Phosphorescence of Flavylium Cation Analogues of Anthocyanins

Fluorescence spectra and lifetimes were determined for 16 synthetic flavylium cation analogues of anthocyanin plant pigments in dry acetonitrile acidified with trifluoroacetic acid (TFA). Phosphorescence was also observed from the lowest excited triplet state for all of the flavylium cations at 77 K in a rigid TFA-acidified isopropanol glass. The fluorescence quantum yields and lifetimes depend in a systematic manner on the nature and position of the substituents on the flavylium chromophore and three specific substitution patterns associated with significant decreases in the fluorescence quantum yield were identified. A 4′-bromo or 4′-iodo substituent in the B-ring of the flavylium cation produced a small but normal heavy-atom effect, reducing the fluorescence quantum yield and the phosphorescence lifetime relative to analogues without the halogen atom. In contrast, three flavylium cations with a 3′-bromo substituent exhibited an “inverse” heavy atom effect, i.e., an increase in the fluorescence quantum yield rather than a decrease, which was rationalized on the basis of the nodal properties of the natural transition orbitals (NTOs) involved in the S0→S1 radiative transition.

Investigation of Mechanical and Microstructural Properties of Polyolefin Rubber and Glass Beads Filled Polypropylene Composites

In the automotive industry and many industries, parts are expected to meet certain requirements with regards to their tensile strength, stiffness, and high impact strength. For this reason, polypropylene homopolymer, which is a fragile polymer widely used in the automotive industry, is combined with additives to reduce its fragility. In this study, the mechanical and microstructural properties of polyolefin rubber and glass bead filled polypropylene composites have been investigated. Polypropylene (PP) was combined with polyolefin rubber (POE) and glass beads (GB) at different weight rates to create the composites and pure polypropylene was compared to the three prepared PP composites; 8% polyolefin rubber by weight, 8% glass bead by weight, and 8% polyolefin rubber and 8% glass bead by weight. The fracture surface examinations of the pure polypropylene (PP), and the polyolefin rubber added PP, glass bead added PP, and polyolefin rubber and glass bead added PP composites were carried out using Scanning Electron Microscopy (SEM). In addition, Energy Dispersive Spectroscopy (EDS) analysis was also performed for the characterization. It was observed that the tensile strength values of the PP composites (PP-8%POE, PP-8%GB, and PP-8%POE-8%GB) showed a slight decrease relative to the pure PP. When rigid glass beads were added to the pure PP polymer main matrix (8% by weight), the stiffness of the composite increased and the modulus of elasticity increased by approximately 8% relative to pure PP. In addition, it was observed that the % elongation at break values of the PP composites (PP-8%POE, PP-8%GB, and PP-8%POE-8%GB) increased significantly relative to the values for pure PP.

53‐3: Worldwide First Real Border‐less and High Resolution Micro‐LED Display

A flexible PI‐less micro‐LED display, 228 PPI, has been achieved by transferring the display devices from rigid glass to plastic. By forming this micro‐LED display on a mold with round edge and lowering the edge radius to 100um, a more cubic waterfall display is realized.

Investigating the role of filler shape on the dynamic mechanical properties of glass‐filled epoxy composites

AbstractThe influence of filler shape and volume fraction on the dynamic mechanical characteristics of rigid glass filler epoxy composites is investigated. Two variants of glass fillers, spherical particle and slender (milled) fibers, are doped into the epoxy matrix till 10% volume fraction. The composites are room temperature cured and tested to measure their viscoelastic properties. The dynamic mechanical analyses performed in the temperature range of 20–180°C at 10 Hz suggest that the milled fiber composites display consistently higher storage and loss moduli, whereas the higher loss factor peaks were noted for the spherical particle composites. The C‐factor, filler reinforcement efficiency of the composites and entanglement density, evaluated from the storage modulus values, indicate that the milled fibers composites are more effective in transferring the loads in both glassy and rubbery zones when compared against the spherical particle case. Also, the filler/matrix adhesion factor (A factor) and the interphase adhesion factor, calculated from the loss factor curves reveal stronger filler/matrix interactions in the case of milled fiber epoxy composites. Interestingly, the filler geometry or volume fraction has only marginal influence on the glass transition temperature of the composites.