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13 pages, 3513 KiB

Open AccessArticle

Advanced Algorithm for Reliable Quantification of the Geometry and Printability of Printed Patterns

by Jongsu Lee and Chung Hwan Kim

Nanomaterials 2023, 13(10), 1597; https://doi.org/10.3390/nano13101597 - 10 May 2023

Viewed by 917

In nanoparticle-based printed electronic devices, the printability of the patterns constituting the device are crucial factors. Although many studies have investigated the printability of patterns, only a few have analyzed and established international standards for measuring the dimensions and printability of shape patterns. [...] Read more.

In nanoparticle-based printed electronic devices, the printability of the patterns constituting the device are crucial factors. Although many studies have investigated the printability of patterns, only a few have analyzed and established international standards for measuring the dimensions and printability of shape patterns. This study introduces an advanced algorithm for accurate measurement of the geometry and printability of shape patterns to establish an international standard for pattern dimensions and printability. The algorithm involves three core concepts: extraction of edges of printed patterns and identification of pixel positions, identification of reference edges via the best-fitting of the shape pattern, and calculation of different pixel positions of edges related to reference edges. This method enables the measurement of the pattern geometry and printability, including edge waviness and widening, while considering all pixels comprising the edges of the patterns. The study results revealed that the rectangle and circle patterns exhibited an average widening of 3.55% and a maximum deviation of 1.58%, based on an average of 1662 data points. This indicates that the algorithm has potential applications in real-time pattern quality evaluation, process optimization using statistical or AI-based methods, and foundation of International Electrotechnical Commission standards for shape patterns. Full article

(This article belongs to the Special Issue Nanomaterials for Printed Electronics and Bioelectronics)

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12 pages, 2329 KiB

Open AccessArticle

Towards Digital Twin Implementation in Roll-To-Roll Gravure Printed Electronics: Overlay Printing Registration Error Prediction Based on Printing Process Parameters

by Anood Shakeel, Bijendra Bishow Maskey, Sagar Shrestha, Sajjan Parajuli, Younsu Jung and Gyoujin Cho

Nanomaterials 2023, 13(6), 1008; https://doi.org/10.3390/nano13061008 - 10 Mar 2023

Viewed by 1583

Abstract

Roll-to-roll gravure (R2Rg) has become highly affiliated with printed electronics in the past few years due to its high yield of printed thin-film transistor (TFT) in active matrix devices, and to its low cost. For printing TFTs with multilayer structures, achieving a high-precision [...] Read more.

Roll-to-roll gravure (R2Rg) has become highly affiliated with printed electronics in the past few years due to its high yield of printed thin-film transistor (TFT) in active matrix devices, and to its low cost. For printing TFTs with multilayer structures, achieving a high-precision in overlay printing registration accuracy (OPRA) is a key challenge to attain the high degree of TFT integration through R2Rg. To address this challenge efficiently, a digital twin paradigm was first introduced in the R2Rg system with an aim to optimize the OPRA by developing a predictive model based on typical input variables such as web tension, nip force, and printing speed in the R2Rg system. In our introductory-level digital twin, errors in the OPRA were collected with the variable parameters of web tensions, nip forces, and printing speeds from several R2Rg printing processes. Subsequently, statistical features were extracted from the input data followed by the training of a deep learning long-short term memory (LSTM) model for predicting machine directional error (MD) in the OPRA. As a result of training the LSTM model in our digital twin, its attained accuracy of prediction was 77%. Based on this result, we studied the relationship between the nip forces and printing speeds to predict the MD error in the OPRA. The results indicated a correlation between the MD error in the OPRA and the printing speed, as the MD error amplitude in the OPRA tended to decline at the higher printing speed. Full article

(This article belongs to the Special Issue Nanomaterials for Printed Electronics and Bioelectronics)

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9 pages, 3946 KiB

Open AccessCommunication

The Effect of Pre-Stretched Substrate on the Electrical Resistance of Printed Ag Nanowires

by Yoon Jae Moon, Chaewon Kim, Eunsik Choi, Dong Yeol Shin and Kyung-Tae Kang

Nanomaterials 2023, 13(4), 719; https://doi.org/10.3390/nano13040719 - 13 Feb 2023

Viewed by 1243

Abstract

One-dimensional nanomaterials have drawn attention as an alternative electrode material for stretchable electronics. In particular, silver nanowires (Ag NWs) have been studied as stretchable electrodes for strain sensors, 3D electronics, and freeform-shaped electronic circuits. In this study, Ag NWs ink was printed on [...] Read more.

One-dimensional nanomaterials have drawn attention as an alternative electrode material for stretchable electronics. In particular, silver nanowires (Ag NWs) have been studied as stretchable electrodes for strain sensors, 3D electronics, and freeform-shaped electronic circuits. In this study, Ag NWs ink was printed on the pre-stretched silicone rubber film up to 40% in length using a drop-on-demand dispenser. After printing, silicone rubber film was released and stretched up to 20% as a cyclic test with 10-time repetition, and the ratios of the resistance of the stretched state to that of the released state (R_stretched/R_released) were measured at each cycle. For Ag NWs electrode printed on the pre-stretched silicone rubber at 30%, R_stretched/R_released at 10% and 20% strain was 1.05, and 1.57, respectively, which is significantly less than about 7 for Ag NWs at the 10% strain without pre-stretched substrate. In the case of 10% strain on the 30% pre-stretched substrate, the substrate is stretched and the contact points with Ag NWs were not changed much as the silicone rubber film stretched, which meant that Ag NWs may slide between other Ag NWs. Ag NWs electrode on the 40% pre-stretched substrate was stretched, strain was concentrated on the Ag NWs electrode and failure of electrode occurred, because cracks occurred at the surface of silicone rubber film when it was pre-stretched to 40%. We confirmed that printed Ag NWs on the pre-stretched film showed more contact points and less electric resistance compared to printed Ag NWs on the film without pre-stretching. Full article

(This article belongs to the Special Issue Nanomaterials for Printed Electronics and Bioelectronics)

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11 pages, 12024 KiB

Open AccessEditor’s ChoiceArticle

Rapid Uniformity Analysis of Fully Printed SWCNT-Based Thin Film Transistor Arrays via Roll-to-Roll Gravure Process

by Yunhyok Choi, Younsu Jung, Reem Song, Jinhwa Park, Sajjan Parajuli, Sagar Shrestha, Gyoujin Cho and Byung-Sung Kim

Nanomaterials 2023, 13(3), 590; https://doi.org/10.3390/nano13030590 - 01 Feb 2023

Cited by 3 | Viewed by 1559

Abstract

The roll-to-roll (R2R) gravure process has the potential for manufacturing single-wall carbon nanotubes (SWCNT)-based thin film transistor (TFT) arrays on a flexible plastic substrate. A significant hurdle toward the commercialization of the R2R-printed SWCNT-TFT array is the lack of a suitable, simple, and [...] Read more.

The roll-to-roll (R2R) gravure process has the potential for manufacturing single-wall carbon nanotubes (SWCNT)-based thin film transistor (TFT) arrays on a flexible plastic substrate. A significant hurdle toward the commercialization of the R2R-printed SWCNT-TFT array is the lack of a suitable, simple, and rapid method for measuring the uniformity of printed products. We developed a probing instrument for characterizing R2R gravure printed TFT, named PICR2R-TFT, for rapidly characterizing R2R-printed SWCNT-TFT array that can present a geographical distribution profile to pinpoint the failed devices in an SWCNT-TFT array. Using the newly developed PICR2R-TFT instrument, the current–voltage characteristics of the fabricated SWCNT-TFT devices could be correlated to various R2R-printing process parameters, such as channel length, roll printing length, and printing speed. Thus, by introducing a characterization tool that is reliable and fast, one can quickly optimize the R2R gravure printing conditions to enhance product uniformity, thereby maximizing the yield of printed SWCNT-TFT arrays. Full article

(This article belongs to the Special Issue Nanomaterials for Printed Electronics and Bioelectronics)

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10 pages, 3333 KiB

Open AccessArticle

Improving Stability of Roll-to-Roll (R2R) Gravure-Printed Carbon Nanotube-Based Thin Film Transistors via R2R Plasma-Enhanced Chemical Vapor-Deposited Silicon Nitride

by Sagar Shrestha, Sajjan Parajuli, Jinhwa Park, Hao Yang, Tae-Yeon Cho, Ji-Ho Eom, Seong-Keun Cho, Jongsun Lim, Gyoujin Cho and Younsu Jung

Nanomaterials 2023, 13(3), 559; https://doi.org/10.3390/nano13030559 - 30 Jan 2023

Cited by 4 | Viewed by 2018

Abstract

Single-walled carbon nanotubes (SWCNTs) have an advantage in printing thin film transistors (TFTs) due to their high carrier mobility, excellent chemical stability, mechanical flexibility, and compatibility with solution-based processing. Thus, the printed SWCNT-based TFTs (pSWCNT-TFTs) showed significant technological potential such as integrated circuits, [...] Read more.

Single-walled carbon nanotubes (SWCNTs) have an advantage in printing thin film transistors (TFTs) due to their high carrier mobility, excellent chemical stability, mechanical flexibility, and compatibility with solution-based processing. Thus, the printed SWCNT-based TFTs (pSWCNT-TFTs) showed significant technological potential such as integrated circuits, conformable sensors, and display backplanes. However, the long-term environmental stability of the pSWCNT-TFTs hinders their commercialization. Thus, to extend the stability of the pSWCNT-TFTs, such devices should be passivated with low water and oxygen permeability. Herein, we introduced the silicon nitride (SiNx) passivation method on the pSWCNT-TFTs via a combination of roll-to-roll (R2R) gravure and the roll-to-roll plasma-enhanced vapor deposition (R2R-PECVD) process at low temperature (45 °C). We found that SiNx-passivated pSWCNT-TFTs showed ± 0.50 V of threshold voltage change at room temperature for 3 days and ±1.2 V of threshold voltage change for 3 h through a Temperature Humidity Test (85/85 test: Humidity 85%/Temperature 85 °C) for both p-type and n-type pSWCNT-TFTs. In addition, we found that the SiNx-passivated p-type and n-type pSWCNT-TFT-based CMOS-like ring oscillator, or 1-bit code generator, operated well after the 85/85 test for 24 h. Full article

(This article belongs to the Special Issue Nanomaterials for Printed Electronics and Bioelectronics)

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14 pages, 3922 KiB

Open AccessArticle

Dielectric Behavior of Thin Polymerized Composite Layers Fabricated by Inkjet-Printing

by Timo Reinheimer, Tim P. Mach, Kevin Häuser, Michael J. Hoffmann and Joachim R. Binder

Nanomaterials 2023, 13(3), 441; https://doi.org/10.3390/nano13030441 - 21 Jan 2023

Viewed by 1251

Abstract

A detailed study of the dielectric behavior of printed capacitors is given, in which the dielectric consists of a thin (<1 µm) ceramic/polymer composite layer with high permittivities of ε_r 20–69. The used ink contains surface-modified Ba_0.6Sr_0.4TiO₃ [...] Read more.

A detailed study of the dielectric behavior of printed capacitors is given, in which the dielectric consists of a thin (<1 µm) ceramic/polymer composite layer with high permittivities of ε_r 20–69. The used ink contains surface-modified Ba_0.6Sr_0.4TiO₃ (BST), a polymeric crosslinking agent and a thermal initiator, which allows the immediate polymerization of the ink during printing, leading to homogenous layers. To validate the results of the calculated permittivities, different layer thicknesses of the dielectric are printed and the capacitances, as well as the loss factors, are measured. Afterwards, the exact layer thicknesses are determined with cross sectional SEM images of ion-etched samples. Then, the permittivities are calculated with the known effective area of the capacitors. Furthermore, the ink composition is varied to obtain different ceramic/polymer ratios and thus different permittivities. The packing density of all composites is analyzed via SEM to show possible pores and validate the target ratio, respectively. The correlation between the chosen ratio and the measured permittivity is discussed using models from the literature. In addition, the leakage current of some capacitors is measured and discussed. For that, the dielectric was printed on different bottom electrodes as the nature of the electrode was found to be crucial for the performance. Full article

(This article belongs to the Special Issue Nanomaterials for Printed Electronics and Bioelectronics)

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10 pages, 3569 KiB

Open AccessArticle

Fully Atomistic Molecular Dynamics Simulation of a TIPS-Pentacene:Polystyrene Mixed Film Obtained via the Solution Process

by Tomoka Suzuki, Antonio De Nicola, Tomoharu Okada and Hiroyuki Matsui

Nanomaterials 2023, 13(2), 312; https://doi.org/10.3390/nano13020312 - 11 Jan 2023

Cited by 1 | Viewed by 1516

Abstract

Organic thin-film transistors using small-molecule semiconductor materials such as 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-P) have been recently studied for the production of flexible and printed electronic devices. Blending a semiconductor with an insulating polymer, such as polystyrene, is known to improve the device performance; however, its [...] Read more.

Organic thin-film transistors using small-molecule semiconductor materials such as 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-P) have been recently studied for the production of flexible and printed electronic devices. Blending a semiconductor with an insulating polymer, such as polystyrene, is known to improve the device performance; however, its molecular-level structure remains unknown. In this study, we performed molecular dynamics (MD) simulations on a mixed system of TIPS-P and atactic polystyrene (aPS) with fully atomistic models to understand the structure of the mixed thin film at the molecular level and the influence on the device properties. To reproduce the deposition from the solution, we gradually reduced the number of toluene molecules in the simulation. The dynamic characteristics of the system, mean squared displacement, diffusion coefficient, density profile, and P₂ order parameter were analyzed. Some of the simulated systems reached the equilibrium state. In these systems, the simulated structures suggested the presence of more TIPS-P molecules on the surface than inside the bulk, even at the low molecular weight of aPS, where phase separation was not observed experimentally. The results of the fully atomistic MD simulations are also a basis for the coarse-grained model to increase the speed of the MD simulation. Full article

(This article belongs to the Special Issue Nanomaterials for Printed Electronics and Bioelectronics)

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16 pages, 12783 KiB

Open AccessArticle

Continuous Patterning of Silver Nanowire-Polyvinylpyrrolidone Composite Transparent Conductive Film by a Roll-to-Roll Selective Calendering Process

by Hakyung Jeong, Jae Hak Lee, Jun-Yeob Song, Faizan Ghani and Dongjin Lee

Nanomaterials 2023, 13(1), 32; https://doi.org/10.3390/nano13010032 - 21 Dec 2022

Cited by 4 | Viewed by 1572

Abstract

The roll-to-roll (R2R) continuous patterning of silver nanowire-polyvinylpyrrolidone (Ag NW-PVP) composite transparent conductive film (cTCF) is demonstrated in this work by means of slot-die coating followed by selective calendering. The Ag NWs were synthesized by the polyol method, and adequately washed to leave [...] Read more.

The roll-to-roll (R2R) continuous patterning of silver nanowire-polyvinylpyrrolidone (Ag NW-PVP) composite transparent conductive film (cTCF) is demonstrated in this work by means of slot-die coating followed by selective calendering. The Ag NWs were synthesized by the polyol method, and adequately washed to leave an appropriate amount of PVP to act as a capping agent and dispersant. The as-coated Ag NW-PVP composite film had low electronic conductivity due to the lack of percolation path, which was greatly improved by the calendering process. Moreover, the dispersion of Ag NWs was analyzed with addition of PVP in terms of density and molecular weight. The excellent dispersion led to uniform distribution of Ag NWs in a cTCF. The continuous patterning was conducted using an embossed pattern roll to perform selective calendering. To evaluate the capability of the calendering process, various line widths and spacing patterns were investigated. The minimum pattern dimensions achievable were determined to be a line width of 0.1 mm and a line spacing of 1 mm. Finally, continuous patterning using selective calendering was applied to the fabrication of a flexible heater and a resistive touch sensing panel as flexible electronic devices to demonstrate its versatility. Full article

(This article belongs to the Special Issue Nanomaterials for Printed Electronics and Bioelectronics)

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6 pages, 1946 KiB

Open AccessArticle

N-Type Printed Organic Source-Gated Transistors with High Intrinsic Gain

by Yudai Hemmi, Yuji Ikeda, Radu A. Sporea, Yasunori Takeda, Shizuo Tokito and Hiroyuki Matsui

Nanomaterials 2022, 12(24), 4441; https://doi.org/10.3390/nano12244441 - 14 Dec 2022

Cited by 5 | Viewed by 1416

Abstract

Source-gated transistors (SGTs) are emerging devices enabling high-gain single-stage amplifiers with low complexity. To date, the p-type printed organic SGT (OSGT) has been developed and showed high gain and low power consumption. However, complementary OSGT circuits remained impossible because of the lack of [...] Read more.

Source-gated transistors (SGTs) are emerging devices enabling high-gain single-stage amplifiers with low complexity. To date, the p-type printed organic SGT (OSGT) has been developed and showed high gain and low power consumption. However, complementary OSGT circuits remained impossible because of the lack of n-type OSGTs. Here, we show the first n-type OSGTs, which are printed and have a high intrinsic gain over 40. A Schottky source contact is intentionally formed between an n-type organic semiconductor, poly{[N,N′-bis(2-octyldodecyl)naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5′-(2,2′-bithiophene)} (N2200), and the silver electrode. In addition, a blocking layer at the edge of the source electrode plays an important role to improve the saturation characteristics and increase the intrinsic gain. Such n-type printed OSGTs and complementary circuits based on them are promising for flexible and wearable electronic devices such as for physiological and biochemical health monitoring. Full article

(This article belongs to the Special Issue Nanomaterials for Printed Electronics and Bioelectronics)

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14 pages, 5691 KiB

Open AccessArticle

Fabrication of Nitrogen-Doped Reduced Graphene Oxide Modified Screen Printed Carbon Electrode (N-rGO/SPCE) as Hydrogen Peroxide Sensor

by Khursheed Ahmad and Haekyoung Kim

Nanomaterials 2022, 12(14), 2443; https://doi.org/10.3390/nano12142443 - 16 Jul 2022

Cited by 14 | Viewed by 2211

Abstract

In recent years, the electrochemical sensing approach has attracted electrochemists because of its excellent detection process, simplicity, high sensitivity, cost-effectiveness, and high selectivity. In this study, we prepared nitrogen doped reduced graphene oxide (N-rGO) and characterized it using various advanced techniques such as [...] Read more.

In recent years, the electrochemical sensing approach has attracted electrochemists because of its excellent detection process, simplicity, high sensitivity, cost-effectiveness, and high selectivity. In this study, we prepared nitrogen doped reduced graphene oxide (N-rGO) and characterized it using various advanced techniques such as XRD, SEM, EDX, Raman, and XPS. Furthermore, we modified the active surface of a screen printed carbon electrode (SPCE) via the drop-casting of N-rGO. This modified electrode (N-rGO/SPCE) exhibited an excellent detection limit (LOD) of 0.83 µM with a decent sensitivity of 4.34 µAµM⁻¹cm⁻² for the detection of hydrogen peroxide (H₂O₂). In addition, N-rGO/SPCE also showed excellent selectivity, repeatability, and stability for the sensing of H₂O₂. Real sample investigations were also carried out that showed decent recovery. Full article

(This article belongs to the Special Issue Nanomaterials for Printed Electronics and Bioelectronics)

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12 pages, 3185 KiB

Open AccessArticle

Effect of Radial Stress on the Nanoparticle-Based Electrolyte Layer in a Center-Wound Roll with Roll-to-Roll Systems

by Jaehyun Noh, Minho Jo, Gyoujin Cho, Sanghoon Nam and Changwoo Lee

Nanomaterials 2022, 12(6), 1014; https://doi.org/10.3390/nano12061014 - 20 Mar 2022

Cited by 1 | Viewed by 2736

Abstract

Recently, slot-die coating based on the roll-to-roll process has been actively used to fabricate nanoparticle-based electrolyte layers because it is advantageous for high-speed processes and mass production of uniformly thick electrolyte layers. In this process, the fabricated electrolyte layer is stored as a [...] Read more.

Recently, slot-die coating based on the roll-to-roll process has been actively used to fabricate nanoparticle-based electrolyte layers because it is advantageous for high-speed processes and mass production of uniformly thick electrolyte layers. In this process, the fabricated electrolyte layer is stored as a wound roll throughout the rewinding process. We analyzed the defects and geometric changes in an electrolyte layer, i.e., gadolinium-doped cerium oxide (GDC), due to the radial stress in the wound roll. We found that the thickness of the coated layer could be decreased by increasing the radial stress, i.e., cracks can be generated in the coated layer if excessively high radial stress is applied to the wound-coated layer. More thickness changes and crack defects were generated with time due to the residual stress in the wound roll. Finally, we analyzed the effects of taper tension profiles on the defects of the coated layer in the wound roll and determined the taper tension profile to minimize defects. Full article

(This article belongs to the Special Issue Nanomaterials for Printed Electronics and Bioelectronics)

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Review

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28 pages, 6261 KiB

Open AccessFeature PaperReview

Control of the Drying Patterns for Complex Colloidal Solutions and Their Applications

by Saebom Lee, Tiara A. M., Gyoujin Cho and Jinkee Lee

Nanomaterials 2022, 12(15), 2600; https://doi.org/10.3390/nano12152600 - 28 Jul 2022

Cited by 14 | Viewed by 4379

Abstract

The uneven deposition at the edges of an evaporating droplet, termed the coffee-ring effect, has been extensively studied during the past few decades to better understand the underlying cause, namely the flow dynamics, and the subsequent patterns formed after drying. The non-uniform evaporation [...] Read more.

The uneven deposition at the edges of an evaporating droplet, termed the coffee-ring effect, has been extensively studied during the past few decades to better understand the underlying cause, namely the flow dynamics, and the subsequent patterns formed after drying. The non-uniform evaporation rate across the colloidal droplet hampers the formation of a uniform and homogeneous film in printed electronics, rechargeable batteries, etc., and often causes device failures. This review aims to highlight the diverse range of techniques used to alleviate the coffee-ring effect, from classic methods such as adding chemical additives, applying external sources, and manipulating geometrical configurations to recently developed advancements, specifically using bubbles, humidity, confined systems, etc., which do not involve modification of surface, particle or liquid properties. Each of these methodologies mitigates the edge deposition via multi-body interactions, for example, particle–liquid, particle-particle, particle–solid interfaces and particle–flow interactions. The mechanisms behind each of these approaches help to find methods to inhibit the non-uniform film formation, and the corresponding applications have been discussed together with a critical comparison in detail. This review could pave the way for developing inks and processes to apply in functional coatings and printed electronic devices with improved efficiency and device yield. Full article

(This article belongs to the Special Issue Nanomaterials for Printed Electronics and Bioelectronics)

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