Ag Grid Electrode Research Articles

Electrohydrodynamic Printing of Ultrafine and Highly Conductive Ag Electrodes for Various Flexible Electronics

AbstractSilver nanoparticle (AgNP) based inks are widely used in printed electronics to form conductive patterns. However, high resolution and high electrical conductivity are still hard to achieve at the same time for the patterning of AgNP‐based electrodes. Herein, Ag patterns with a high resolution of sub‐10 µm and a high conductivity are realized by the electrohydrodynamic (EHD) printing. The parameters including the composition of Ag ink, printing speed, voltage, and working height are carefully controlled to increase the resolution, and the process window of the cone jet mode is established. With the help of the finite element simulation, the generation mechanism of the Taylor cone is clarified. Ag electrodes with various patterns and shapes are easily produced, which exhibited excellent patterning qualities, such as superior uniformity and flatness, narrow spacing, and clear edge definition. Finally, flexible light‐emitting diode (LED) circuits, transparent heaters, and supercapacitors are fabricated by EHD printed Ag grid electrodes. These results indicate that this work provides a simple and scalable strategy for fabricating ordered metal conductive patterns in the emerging printed electronics.

Efficient Semitransparent Organic Solar Cells Enabled by Ag Grid Electrodes and Optical Coupling Layers.

Semitransparent organic solar cells (ST-OSCs) show great promise for building integrated photovoltaic systems. The balance between power conversion efficiency (PCE) and average visible transmittance (AVT) is a key point of ST-OSCs. We developed a novel semitransparent organic solar cell (ST-OSC) with high PCE and AVT for building integrated renewable energy applications. We used photolithography to fabricate Ag grid bottom electrodes with high figures of merit of 292.46. We also used an optimized active layer of PM6 and Y6, achieving a PCE of 10.65% and an AVT of 22.78% for our ST-OSCs. By adding optical coupling layers of CBP and LiF alternately, we further increased the AVT to 27.61% and the PCE to 10.87%. Importantly, the balance of PCE and AVT can be achieved by the integrated optimization of the active and optical coupling layers, which leads to a significant increase in light utilization efficiency (LUE). These results are of great importance for particle applications of ST-OSCs.

Carbon nanotube/silicon heterojunction solar cell with an active area of 4 cm2 realized using a multifunctional molybdenum oxide layer

Carbon nanotube (CNT)/silicon heterojunction solar cells have been extensively studied owing to the ease of junction fabrication. Encouraging power conversion efficiencies (PCEs) have been reported; however, many of them are limited to small cells (<1 cm2). Herein, we report MoOx as a multifunctional layer that enables the size and performance enhancement. A 4 cm2-sized MoOx–CNT/n-Si solar cell with a PCE of 10.0% was realized via simple processes: dispersion–filtration–transfer for the CNT layer, hot-wire oxidation–sublimation deposition for the MoOx layer, mask-deposition for the Ag grid electrodes, and spin-coating for the polymethyl methacrylate anti-reflective layer. The MoOx layer played an essential role as a blocking layer to prevent direct contact and current leakage between Ag and n-Si while allowing the electrical conduction between Ag and CNT. It also served as a p-type dopant for the CNTs, which enhanced the electrical conduction and separation of electron–hole pairs at the heterojunction, and as an enhancer for the anti-reflective effect of the MoOx–CNT layer. Post-thermal annealing of MoOx was found to be crucially important, and the role of MoOx was also evaluated. This combination of a multifunctional MoOx layer with a metal grid electrode provides a facile route for practical CNT/Si heterojunction solar cells.

Ag/Cu plating to improve Ag grid electrodes of the recycled c-Si solar cells

Ag/Cu plating to improve Ag grid electrodes of the recycled c-Si solar cells

Development of Electrochromic Device with Poly(3,4-ethylenedioxythiophene) on Invisible Silver-Grid Transparent Electrode

Electrochromic (EC) reaction is defined as a reversible color change which induced by the electrochemical redox reactions. The EC device is promising as an optical modulation device such as a display and a window. However, a flexibilities of the EC device is unsatisfied because conventional EC device consists of transparent conductive oxide on the glass substrate. To overcome this, we have developed a gravure offset printed invisible Ag-grid transparent electrodes by using Ag-nanoparticles ink,[1] and demonstrated that a powder electroluminescent device by this transparent electrode showed the high bending stability.[2], [3] Therefore, it is also expected the realization of EC device showing high bending durability.In this study, the novel EC device composed of poly(3,4-ethyenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) has been fabricated on a gravure offset printed fine Ag-grid transparent electrode and evaluated optical and electrochemical properties. Scanning the potential from 0 V (vs. Ag/Ag+) to the negative direction, the cathodic current due to the reductive reaction of PEDOT:PSS was observed, and the absorbance correspond to the coloration of PEDOT:PSS was increased. Then, when scanning the potential to the positive direction, the anodic current due to the oxidative reaction of PEDOT:PSS was observed, and the absorbance was decreased. This changing in the absorbance were observed several tens of times. These evaluation results demonstrate that PEDOT:PSS develops a reversible color change with the EC reaction on the fine silver-grid transparent electrode. Reference [1] M. Ohsawa, N. Hashimoto, Mater. Res. Express, 5, 085030 (2018).[2] N. Takeda, S. Tsuneyasu, K. Yanagawa, N. Hashimoto, M. Ohsawa, T. Satoh, Electron. Lett., in press.[3] M. Ohsawa, N. Hashimoto, N. Takeda, S. Tsuneyasu, T. Satoh, Flex. Print. Electron. (under review). Figure 1

In brief

PAGE 632 Chinese researchers propose a symbol cyclic reconstruction scheme for universal-filtered multi-carrier systems (UFMC). The overlap-add technique is used to lower the computational complexity of the system transmitter, with ISI cancellation used at the receiver to remove interference between neighbouring symbols. Simulation results show the superiority of the scheme over state-of-the-art systems. PAGE 616 Researchers from Iran present a monitoring technique for tracking the state-of-health of batteries, suitable for use in battery management systems. The method can detect early degradation of batteries by monitoring the switching and battery transitions in a battery management system. Experiments on a typical charge balancing circuit verify the performance of the technique. Block diagram of SCR-UFMC with multipath fading channels. PAGE 589 Indian researchers propose a novel estimation technique for a noise-influenced electronic circuit, unifying the Carleman linearisation with the Fokker-Planck equation for Itô's Stochastic Differential Equations. Numerical simulation results are presented for a benchmark tunnel diode oscillator circuit. The method may prove useful for estimating state trajectories under the influence of randomness when observations are not possible. Laboratory test bench. PAGE 612 A collaboration of researchers from Japan present an evaluative study on the current and luminance characteristics of powder electroluminescent devices prepared on gravure offset-printed invisible Ag-grid electrodes. Results show that the luminance is strongly dependent on the transparency and light-extraction efficiency of the Ag-grid electrodes. Flow of the proposed estimation technique.. PAGE 609 Researchers from China propose a wideband differential filtering power divider, using a three-lined coupled structure with multiple lumped elements. Compared with other differential filtering power dividers, the proposed design shows the advantages of a wide bandwidth, compact size and low insertion loss. A prototype validates the simulated results. Optical microscopy image of the emitted light from PELDs on the Ag-grid electrodes. Photograph of the proposed wideband differential filtering power divider.

Enhanced electroluminescence in fully printable powder electroluminescent device with flexible invisible silver‐grid transparent electrode

Powder electroluminescent devices (PELDs) have a high potential for commercial application because of flat light emission devices and simple printing process fabrication with low-cost production, without semiconductor processes using vacuum and plasma. In conventional PELDs, indium tin oxide (ITO) has been used as a transparent electrode. However, ITO is unfavourable in flexible electronic devices due to its intrinsic brittleness. The authors evaluated the current and luminance characteristics of PELDs prepared on gravure offset-printed invisible silver-grid (Ag-grid) electrodes that were laminated with and without poly(3,4-ethylenedioxythiophene):poly(styrenesulphonate) (PEDOT:PSS) transparent electrodes. The PELD on the Ag-grid laminated with PEDOT:PSS electrode shows the maximum luminance of ∼250 cd/m2 at 200 μm spacing, which is five-fold greater than the luminance of PELD without PEDOT:PSS electrode lamination.

Flexible powder electroluminescent device on transparent electrode of printed invisible silver-grid laminated with conductive polymer

Invisible Ag-grid transparent electrodes at a line width of the Ag-grid of 5 μm, spacing between the grid lines of 150 μm and a line thickness of 0.6 μm have been prepared on a 50 μm thick flexible polyethylene naphthalate (PEN) film substrate by a conventional gravure offset printing using our newly developed Ag nanoparticle ink. Furthermore, the Ag-grid electrode was laminated with a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) layer. The Ag-grid laminated with PEDOT:PSS (Ag-grid/PEDOT) transparent electrode was applied to a commercial alternating-current powder electroluminescent device (ACPELD) as an ITO replacement. The as-prepared Ag-grid/PEDOT-based ACPELD shows uniform luminescence with a luminance of 292 cd m−2 at 150 V0-p and 2 kHz. Repeated bending durability of the fabricated ACPELD was evaluated by a cyclic bending test at a bending radius of 1.5 mm up to 20 000 bending cycles. Luminance of the Ag-grid/PEDOT-based ACPELD is stable throughout the bending cycles compared to that of an ITO-based ACPELD. Luminance of the 20 000 cycle-bended Ag-grid/PEDOT-based ACPELD maintains 97% of that of the as-prepared. These results demonstrate that the Ag-grid/PEDOT on PEN-based ACPELDs develop stable luminance characteristics throughout the bending cycles.

Optical and Electrical Properties of Multilayer Grid Electrodes for Highly Durable Transparent Conductive Electrodes

We report on the optical and electrical properties of MgZnO/Ag/MgZnO (MAM) grid electrodes grown at room temperature; these are proposed as an alternative to metal-based grid electrodes to meet the requirement for high stability in a harsh environment. The optical transmittance of Ag grid electrodes improved when the Ag grid layer was embedded in an MgZnO grid layer regardless of the fill factor. This improvement depends critically on the Ag grid layer thickness in the MAM grid electrodes. The Haack figure of merit for a MAM grid electrode with a 20 nm-thick Ag grid layer was approximately threefold higher than that of an Ag grid electrode. The electrode has an average transmittance of 85.8% at wavelengths range from 400 to 1100 nm and a sheet resistance of 26.9 Ω/sq. These results indicate that MAM grid electrodes can be an alternative to metal-based grid electrodes in optoelectronic devices that require stable wideband operation in a harsh environment and over a wide wavelength region.

Bending reliability of flexible transparent electrode of gravure offset printed invisible silver-grid laminated with conductive polymer

Invisible Ag-grid transparent electrodes at a line width of the Ag-grid of 5 μm and a line thickness of 0.6 μm have been prepared on a flexible polyethylene naphthalate (PEN) film substrate by a conventional gravure offset printing using our newly developed Ag nanoparticle ink. Furthermore, the Ag-grid electrodes were laminated with a poly(3,4‑ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) layer. The bending flexibilities and repeated bending durabilities of the transparent electrodes have been investigated via bending tests. The Ag-grid laminated with PEDOT:PSS electrode shows no noticeable resistance change until the electrode is bended to an outer bending radius of 1.3 mm. Moreover, the Ag-grid laminated with PEDOT:PSS electrode shows no noticeable resistance change throughout the 10,000 outer bending cycles at a bending radius of 1.5 mm. The results show that the laminating with PEDOT:PSS enhances the bending reliability of the transparent electrodes.

Flexible transparent electrode of gravure offset printed invisible silver-grid laminated with conductive polymer

Invisible Ag-grid transparent electrodes with a variety of spacing between the Ag-grid lines of 100, 150, 200, 300, 500 and 1000 μm at a constant line width of the Ag-grid of 5 μm and a constant thickness of the Ag-grid of 0.6 μm have been prepared by a conventional gravure offset printing using our newly developed Ag nanoparticle ink. In optimizing the Ag-grid electrodes, the transmittance is up to 98% in the visible light region and the sheet resistance is down to 3 Ω/□. Moreover, the Ag-grid electrodes have been laminated with a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) layer. In the Ag-grid laminated with PEDOT:PSS electrodes, the transmittance is up to 96% in the visible light region and the sheet resistance is down to 4 Ω/□. The Ag-grid laminated with PEDOT:PSS electrodes would have potential applications as flexible and transparent conductive films in optoelectronics and photovoltaics.

Embedded Ag Grid Electrodes as Current Collector for Ultraflexible Transparent Solid-State Supercapacitor.

Flexible transparent solid-state supercapacitors have attracted immerse attention for the power supply of next-generation flexible "see-through" or "invisible" electronics. For fabrication of such devices, high-performance flexible transparent current collectors are highly desired. In this paper, the utilization of embedded Ag grid transparent conductive electrodes (TCEs) fabricated by a facile soft ultraviolet imprinting lithography method combined with scrap techniques, as the current collector for flexible transparent solid-state supercapacitors, is demonstrated. The embedded Ag grid TCEs exhibit not only excellent optoelectronic properties (RS ∼ 2.0 Ω sq-1 and T ∼ 89.74%) but also robust mechanical properties, which could meet the conductivity, transparency, and flexibility needs of current collectors for flexible transparent supercapacitors. The obtained supercapacitor exhibits large specific capacitance, long cycling life, high optical transparency (T ∼ 80.58% at 550 nm), high flexibility, and high stability. Owing to the embedded Ag grid TCE structure, the device shows a slight capacitance loss of 2.6% even after 1000 cycles of repetitive bending for a bending radius of up to 2.0 mm. This paves the way for developing high-performance current collectors and thus flexible transparent energy storage devices, and their general applicability opens up opportunities for flexible transparent electronics.

Modification of the Highly Conductive PEDOT:PSS Layer for Use in Silver Nanogrid Electrodes for Flexible Inverted Polymer Solar Cells.

Silver nanogrid based flexible transparent electrode is recognized as the most promising alternative to ITO electrode for organic electronics, owing to its low production cost and excellent flexibility. Typically, a highly conductive thin film coating layer, such as highly conductive PEDOT:PSS (HC-PEDOT:PSS) is usually deposited onto the Ag-grid electrode to smooth the surface and to minimize the sheet resistance. In this paper, we found that inverted flexible polymer solar cells with structure of Ag-grid/HC-PEDOT:PSS/ZnO/photoactive layer/MoO3/Al generally exhibits strong S-shaped J-V curves, which could be eliminated by light-soaking treatment. Kelvin probe force microscope (KPFM) measurement proved that a large work function (WF) difference (0.70 eV) between HC-PEDOT:PSS and ZnO is the main reason for the formation of S-shape. White light soaking of the Ag-grid/HC-PEDOT:PSS gradually decreased the WF of HC-PEDOT:PSS from 5.10 to 4.60 eV, leading to a reduced WF difference between HC-PEDOT:PSS and ZnO from 0.70 to 0.38 eV. Such a WF difference decrease was believed to be the working mechanism for the light-soaking effect in this flexible device. Based on this finding, the HC-PEDOT:PSS solution was then modified by doping with polyethylenimine (PEI) and aqueous ammonia. The modified PEDOT:PSS film is characteristic of adjusting WF through varying PEI doping concentrations. By using such a modified PEDOT:PSS layer, light-soaking-free flexible inverted polymer solar cell with a power conversion efficiency of 6.58% was achieved for PTB7-Th:PC71BM cells. The current work provides a useful guideline for interfacial modification for Ag-grid based flexible electrode.

Metallic Grid Electrode Fabricated via Flow Coating for High-Performance Flexible Piezoelectric Nanogenerators

Transparent conducting electrodes (TCEs) based on metallic grid structures have been extensively explored for use in flexible and transparent electronics according to their excellent conductivity and flexibility. Previous fabrication methods have been limited by the complexity and expense of their processes. Here, we have introduced a simple and cost-effective flow-coating method for preparing flexible and transparent metallic grid electrodes using silver nanoparticles (AgNPs). The process comprises only two steps, including patterning and sintering the horizontal AgNPs lines, followed by patterning and sintering the longitudinal AgNPs lines. The grid width could be easily controlled by varying the concentration of the AgNP solution and the grid spacing could be controlled by varying the distance moved by a translation stage between intermittent stops. The optimized Ag grid electrode exhibited an optical transmittance at 550 nm of 86% and a sheet resistance of 174 Ω/sq. The resulting Ag grid electrodes we...

Effect of geometric lattice design on optical/electrical properties of transparent silver grid for organic solar cells.

Silver (Ag) grid transparent electrode is one of the most promising transparent conducting electrodes (TCEs) to replace conventional indium tin oxide (ITO). We systematically investigate an effect of geometric lattice modifications on optical and electrical properties of Ag grid electrode. The reference Ag grid with 5 μm width and 100 μm pitch (duty of 0.05) prepared by conventional photo-lithography and lift-off processes shows the sheet resistance of 13.27 Ω/sq, transmittance of 81.1%, and resultant figure of merit (FOM) of 129.05. Three different modified Ag grid electrodes with stripe added-mesh (SAM), triangle-added mesh (TAM), and diagonal-added mesh (DAM) are suggested to improve optical and electrical properties. Although all three of SAM, TAM, and DAM Ag grid electrodes exhibit the lower transmittance values of about 72 - 77%, they showed much decreased sheet resistance of 6 - 8 Ω/sq. As a result, all of the lattice-modified Ag grid electrodes display significant improvement of FOM and the highest value of 171.14 is obtained from DAM Ag grid, which is comparable to that of conventional ITO electrode (175.46). Also, the feasibility of DAM Ag gird electrode for use in organic solar cell is confirmed by finite difference time domain (FDTD) simulations. Unlike a conventional ITO electrode, DAM Ag grid electrode can induce light scattering and trapping due to the diffuse transmission that compensates for the loss in optical transparency, resulting in comparable light absorption in the photo active layer of poly(3-hexylthiophene) (P3HT): [6,6]-phenyl-C61-butyric acid methyl ester (PC₆₀BM). P3HT:PC₆₀BM based OSCs with the DAM Ag grid electrode were fabricated, which also showed the potential for ITO-free transparent electrode.

Fabrication of a flexible Ag-grid transparent electrode using ac based electrohydrodynamic Jet printing

In the dc voltage-applied electrohydrodynamic (EHD) jet printing of metal nanoparticles, the residual charge of droplets deposited on a substrate changes the electrostatic field distribution and interrupts the subsequent printing behaviour, especially for insulating substrates that have slow charge decay rates. In this paper, a sinusoidal ac voltage was used in the EHD jet printing process to switch the charge polarity of droplets containing Ag nanoparticles, thereby neutralizing the charge on a polyethylene terephthalate (PET) substrate. Printed Ag lines with a width of 10 µm were invisible to the naked eye. After sintering lines with 500 µm of line pitch at 180 °C, a grid-type transparent electrode (TE) with a sheet resistance of ∼7 Ω sq−1 and a dc to optical conductivity ratio of ∼300 at ∼84.2% optical transmittance was obtained, values that were superior to previously reported results. In order to evaluate the durability of the TE under bending stresses, the sheet resistance was measured as the number of bending cycles was increased. The sheet resistance of the Ag grid electrode increased only slightly, by less than 20% from its original value, even after 500 cycles. To the best of our knowledge, this is the first time that Ag (invisible) grid TEs have been fabricated on PET substrates by ac voltage applied EHD jet printing.

Efficient Polymer Solar Cells on Opaque Substrates with a Laminated PEDOT:PSS Top Electrode

AbstractSolution processed polymer:fullerene solar cells on opaque substrates have been fabricated in conventional and inverted device configurations. Opaque substrates, such as insulated steel and metal covered glass, require a transparent conducting top electrode. We demonstrate that a high conducting (900 S cm−1) PEDOT:PSS layer, deposited by a stamp‐transfer lamination technique using a PDMS stamp, in combination with an Ag grid electrode provides a proficient and versatile transparent top contact. Lamination of large size PEDOT:PSS films has been achieved on variety of surfaces resulting in ITO‐free solar cells. Power conversion efficiencies of 2.1% and 3.1% have been achieved for P3HT:PCBM layers in inverted and conventional polarity configurations, respectively. The power conversion efficiency is similar to conventional glass/ITO‐based solar cells. The high fill factor (65%) and the unaffected open‐circuit voltage that are consistently obtained in thick active layer inverted geometry devices, demonstrate that the laminated PEDOT:PSS top electrodes provide no significant potential or resistive losses.