Search

With the increasing demand for compact, lightweight, cost‐effective, and high‐performance radiofrequency (RF) devices, the development of low‐profile antennas becomes crucial. This article presents a study of a novel carbon–cellulose‐based paste intended for screen printing RF devices. The investigation specifically explores the application of high‐reactivity carbon mixture (HRCM) particles as conductive fillers. The results demonstrate that optimal electrical conductivity values and discrete electromagnetic dipole performances can be achieved at lower concentrations of solid conductive material compared to conventional pastes, for similar applications. This offers benefits in terms of total cost, material consumption, and environmental impact. The paste formulation showcases a complex non‐Newtonian behavior, where yielding flow and thixotropicity are found to be independent and dependent on preshear conditions, respectively. This behavior can be attributed to the network orientation and rearrangement of filler structures within the paste system, which in turn are responsible for filler pattern uniformity and overall printing quality. Compared to traditional conductive materials, HRCM pastes are proven to be a viable alternative for RF devices fabrication, including printed Wi‐Fi antennas. [ABSTRACT FROM AUTHOR]

With the constant increase of electronic waste globally, society is demanding and governments are boosting the development of electronics with less pollutant materials and reduced environmental impact. One way to achieve this is to implement materials that are functional and structural at the same time, reducing material use and assembling parts. Further, printing techniques, such as screen printing, reduce considerably costs and time compared with conventional electronics; combined with methods to conform printed electronics to a 3D shape, such as thermoforming, allow to obtain nonplanar surface electronics simply and efficiently. Herein, screen‐printable inks made of styrene–ethylene/butylene–styrene and different aspect‐ratio carbon‐based materials for conformable electronics are reported. The inks are prepared with carbon black, carbon nanotubes, and reduced graphene oxide as conductive fillers, printed on a flexible substrate and thermoformed. Carbon black and carbon nanotube samples are functional after the process, with conductivities of 96 and 141 S m−1 for the best performing sample of each filler, respectively. Rheological, morphological, thermal, and electrical properties of the materials are also characterized. This study shows the influence of the filler's type and aspect ratio on the morphology and electrical conductivity of the printed materials before and after thermoforming. [ABSTRACT FROM AUTHOR]

This work presents the development of fully printed, large‐area, semi‐transparent Dye‐Sensitized Solar Cells (DSSCs) using TiO2 nanoparticles treated with TiCl4, a “D35” push‐pull dye sensitizer, and I3−/I− redox mediator. Cells with areas of 4 and 200 cm2 were printed using hexagonal, stripe, and standard designs, employing digital materials deposition (DMD) technology. The porous films printed via DMD, confirmed by scanning electron microscopy (SEM), improved solar cells performance by enhancing the Open Circuit Voltage (Voc) and fill factor (FF). The hexagonal design, in particular, facilitated better electrolyte impregnation in the TiO2 mesoporous structure, boosting current density. This design yielded a power conversion efficiency (PCE) of 7.05% for 4 cm2 DSSCs, surpassing the stripe (5.50%) and standard (5.48%) designs. Its higher performance can be attributed to lower interfacial charge recombination rates and improvedcharge transfer and collection efficiency. Photophysical measurements indicated faster charge transfer rates in hexagonal cells (≈ 1.3  ×  109s−1) compared to the stripe (9.8  ×  108 s−1) and standard (9.5  ×  108 s−1) designs. Hence, our work highlights the potential of hexagonal design to improve both efficiency and transparency while reducing material consumption, offering a promising approach for manufacturing semi‐transparent solar cells. [ABSTRACT FROM AUTHOR]

This study presents the development of a novel screen printable quasi‐solid polymer electrolyte (p‐QSPE) for Electrochromic Displays (ECDs) applications. p‐QSPE is composed of three key components: polyvinylidene fluoride (PVDF), a high‐dielectric constant polymer that ensures high ionic conductivity in solid‐state; glyceril propoxy triacrylate (GPTA), a UV‐cross‐linkable monomer that provides structure and durability for overprinting; titanium dioxide (TiO₂) nanoparticles, which modulate the electrolyte's rheological properties for screen printing; reducing the solvent (PC:EC) content to only 35.90 wt.%. Electrochemical Impedance Spectroscopy (EIS) revealed that this well‐designed formulation achieved an ionic conductivity of 1.17 × 10−3 S cm−1 at room temperature, surpassing the threshold required for commercial applications. Moreover, p‐QSPE facilitated the production of fully screen printed ECDs in an industrial printing line, streamlining their production process and achieving an optimal balance between printability, overprint resilience, and device performance. Operational tests for the ECDs showed fast switching times (<6 s for t90 and <2 s for t75) across a wide temperature range (−20 °C to 80 °C). Additionally, the electrolyte demonstrated low charge consumption (2.10 ± 0.11 mC cm−2) and a lifespan exceeding 10 000 cycles. These results highlight the potential of p‐QSPE as a screen printable, high‐performance electrolyte, capable of advancing ECD manufacturing by enabling the production of fully screen‐printed, performing ECDs. [ABSTRACT FROM AUTHOR]

Within this work, we investigate the potential to optimize the screen‐printed front side metallization of silicon heterojunction (SHJ) solar cells. Three iterative experiments are conducted to evaluate the impact of the utilized fine mesh screen configurations and grid layout adaption (finger pitch) for the front side metallization on silver laydown and electrical performance of the solar cells. With respect to the screen configuration, we compare the performance of a fine‐mesh knotless screen to a conventionally angled screen demonstrating an additional gain of Δη = +0.1%abs due to reduced shading losses. Additionally, a grid layout is improved by increasing the number of contact fingers from 120 to 156. Furthermore, the current possibility to push the fine‐line printing process for low‐temperature pastes to the limit is investigated by reducing the nominal finger width wn to 20, 18, and 15 μm. It is shown that even the smallest nominal width of wn = 15 μm can be printed with high quality, leading to an additional efficiency gain of Δη = +0.15%abs as well as a reduction of silver paste laydown by −5 mg. Finally, a batch of champion cells is fabricated by applying the findings of the previous experiments, which results in a maximum efficiency of ηmax = 23.2%. Compared to the reference group without optimization, this corresponds to a gain of Δη = +0.17%abs, which comes along with an additional decrease of the silver paste laydown by approximately −2 mg. This emphasizes the significance of consistent optimization of the screen‐printing process in terms of cell performance and resource utilization for SHJ solar cells. [ABSTRACT FROM AUTHOR]

Strain sensors from conducting polymer hydrogel have been widely employed in various wearable devices, electronic skins, and biomedical applications. These sensors provide outstanding flexibility and high sensitivity by integrating conducting polymer with hydrogels, making them particularly suitable for monitoring human motion and physiological signals like heart rate or muscle activity. Despite their extensive application potential, conducting polymer hydrogel face several technical challenges in practical use, including poor mechanical properties, lack of long‐term stability, and difficulty in customizable design. This work introduces a method for fabricating a multipedal strain sensor using poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS)/polyvinyl alcohol (PVA) dimethyl sulfoxide (DMSO)hydrogels through screen printing and demonstrates its application in human motion monitoring. The multipedal strain sensor demonstrates a low Young's modulus (200 kPa), high stretchability (400%), and excellent mechanical cyclic stability (3000 cycles). Furthermore, this strain sensor is further applied to detect human movements such as chewing, smiling, fist clenching, arm bending, and carotid pulse monitoring. Comparative analysis between the multipedal‐designed sensor and the non‐designed sensor highlights the enhanced sensing capabilities of the multipedal sensor. The design of this multipedal sensor holds the potential to broaden the design concepts for strain sensors and offers new insights for wearable devices and electronic skins. [ABSTRACT FROM AUTHOR]

Flexible wearable electronics are in urgent need of advanced micro‐energy storage devices. MXenes are widely used in supercapacitors because of their excellent conductivity and hydrophilicity. Nevertheless, MXene‐based supercapacitors typically exhibit low capacitance and unsatisfied rate performance, particularly in the solid compact MXene film electrode with limited porosity and/or ion diffusion paths. Here, the synthesis of MXene inks with enlarged interlayer spacing for facilitated ion diffusion kinetics by intercalating lithium ions is reported. The ion‐intercalated MXene inks are further screen‐printed for scalable production of MXene‐based micro‐supercapacitors (MSCs). Benefiting from such an electrode architecture design, as well as the wide voltage window of 21 m bis(trifluoromethane)sulfonimide lithium (LiTFSI) water‐in‐salt electrolyte, the device exhibits impressive areal capacitance (252 mF cm−2), much‐improved rate performance (capacitance retention rate as high as 80%), excellent cyclic stability (retains 98.4% of initial capacitance after 10 000 cycles) and flexibility, showing great potential in the field of wearable intelligent electronics. [ABSTRACT FROM AUTHOR]

Measurements of Young's modulus and residual stresses of screen‐printed ink layers using a bulge test on coated polyimide‐based membranes are proposed in this work. The applied bulge test monitors the deflection of membranes under pressure with interferometry. The obtained Young's modulus ranges from 6 to 8 GPa for a carbon blend‐based ink and is around 12 GPa for a silver nanoparticle ink. These values are compared with standard nanoindentation and show good agreement. Besides, the residual stresses range from −4 to 8 MPa for the carbon blend‐based ink, while the silver ink is measured around −10 MPa. The use of the membrane‐based method underlines the influence of exact deposition and curing conditions on the ink film material properties. The impact of the substrate on the ink layer properties, such as the thickness and its uniformity, is discussed, especially with regard to the heat treatment of the membrane. [ABSTRACT FROM AUTHOR]

Redesigning anode structures in Li‐ion batteries (LIBs) has been a focus of research aimed at surpassing the energy density of conventional LIBs. Although anode‐free LIBs present a promising architecture, their low Coulombic efficiency is a major drawback. This paper introduces a novel hybrid anode that integrates the current collector (CC) and active materials into a single, cohesive porous structure, which supports both de/intercalation and de/plating reactions. The hybrid anode consists of a porous Cu matrix with embedded ZrO2 powders and graphite; the quantity of graphite is only a third of that present in a traditional graphite anode. The porous structure and additives enhance the electrochemical performance of the hybrid anode by minimizing the Li–electrolyte interactions, forming a stable solid–electrolyte interface and Li4Zr3O8 passivation layer, and reducing the nucleation overpotential. Especially, the unique surface morphology, characterized by a negative curvature between sintered Cu particles, lowers the diffusion potential, which further reduces the nucleation overpotential. Additionally, the periodic mesh‐imprinted top surface, created via screen printing, promotes uniform Li plating. The results demonstrate that the cycling performance and energy density offered by the fabricated hybrid anode are superior to those of conventional graphite anodes. [ABSTRACT FROM AUTHOR]

Hybrid organic‐inorganic perovskite solar cells (PSCs) have rapidly advanced in the new generation of photovoltaic devices. As the demand for energy continues to grow, the pursuit of more stable, highly efficient, and cost‐effective solar cells has intensified in both academic research and the industry. Consequently, the development of scalable fabrication techniques that yield a uniform and dense perovskite absorber layer with optimal crystallization plays a crucial role to enhance stability and higher efficiency of perovskite solar modules. This review provides a comprehensive summary of recent advancements, comparison, and future prospects of scalable deposition techniques for perovskite photovoltaics. We discuss various techniques, including solution‐based and physical methods such as blade coating, inkjet printing (IJP), screen printing, slot‐die coating, physical vapor deposition, and spray coating that have been employed for fabrication of perovskite modules. The advantages and challenges associated with these techniques, such as contactless and maskless deposition, scalability, and compatibility with roll‐to‐roll processes, have been thoroughly examined. Finally, the integration of multiple subcells in perovskite solar modules is explored using different scalable deposition techniques. [ABSTRACT FROM AUTHOR]

Energy‐harvesting technologies offer a sustainable, maintenance‐free alternative to conventional energy‐storage solutions in distributed low‐power applications. Flexible thermoelectric generators (TEGs) can generate electric power from a temperature gradient, even on complex surfaces. Organic materials are ideal candidates for flexible TEGs due to their good solution‐processability, natural abundance, low weight, and flexibility. Electronic and thermoelectric properties of organic materials have steadily progressed, while device architectures leveraging their advantages are largely missing. Here, a design and fabrication method are proposed for producing fully screen‐printed, flexible monolithic organic TEGs scalable up to m2, compatible with any screen‐printable ink. This approach is validated, along with its scalability, by printing TEGs composed of two different active inks, in three configurations, with up to 800 thermoelements, with performances well matching simulations based on materials parameters. It is demonstrated that by using an additive‐free graphene ink, a remarkable power density of 15 nW cm−2 at ΔT = 29.5 K can be achieved, with an estimated weight‐normalized power output of 1 µW g−1, highlighting a strong potential in portability. Owing to such power density, only limited areas are required to generate microwatts, sufficient for operating low‐power electronic devices such as sensors, and wearables. [ABSTRACT FROM AUTHOR]

Summary: A dual‐band, wearable coplanar microstrip patch antenna (CPW) integrated with electromagnetic bandgap structure (EBG) to operate dual wireless bands at 2.48 GHz industrial, scientific, and medical band (ISM) and 5.2 GHz WLAN. The proposed textile wearable antenna and EBG structure are screen‐printed using silver conductive ink on the cotton polyester substrate (εr = 1.6) for flexible wearable applications. A 3 × 3 EBG array is realized by a concentric square patch surrounded by the annular square ring to reduce back radiation and increase the forward gain and front‐back ratio. The proposed EBG‐backed antenna, compared with the conventional CPW‐fed antenna, improves forward gain from 2.18 to 6.59 dB at 2.48 GHz and 3.5 to 7.03 dB at 5.2 GHz. Moreover, the EBG array is used to isolate the human body from the antenna and reduces the specific absorption rate (SAR). The antenna is performed with a human phantom tissue model, which exhibits a specific absorption rate of 0.12 W/kg, and 0.260 W/kg for 1 g tissue at 2.48 GHz and 5.2 GHz, respectively. [ABSTRACT FROM AUTHOR]

LiFePO4 (LFP) is widely used as cathode material for its low cost, high safety, and good thermal properties. It is one of the most exploited cathode materials for commercial Li‐ion batteries (LIBs). Herein, we present a screen‐printing method to prepare a LFP composite cathode, and a rational combination of the typical composite solid electrolytes (CSE) consisting of polyethylene oxide (PEO)/Li‐salt (LiTFSi) electrolyte with ceramic filler (LLZO or Li6.4La3Zr1.4Ta0.6O12 (LLZTO)) has been successfully demonstrated for SSB. The prepared CSE offers: i) a promising ionic conductivity (0.425 mS cm−1 at 60 °C), ii) a wide electrochemical window (>4.6 V), iii) a high Li‐ion transference number (tLi+=0.44), iv) a good interfacial compatibility with the electrode, v) a good thermal stability, and vi) a high chemical stability toward Li metal anode. The Li/CSE/Li symmetric cells can be cycled for more than 1000 h without Li‐dendrites growth at a current density of 0.2 mA cm−2. The final cell screen‐printed LFP composite cathode (LFP+LLZO)//Li metal displays a high reversible specific capacity of 140 mAh g−1 (0.1 C) and 50 mAh g−1 (0.5 C) after 1st and 500th cycles. [ABSTRACT FROM AUTHOR]

Efficient metal contact formation is pivotal for the production of cost‐effective, high‐performance crystalline silicon (Si) solar cells. Traditionally, screen‐printed silver (Ag) contacts on the front surface have dominated the industry owing to their simplicity, high throughput, and significant electrical benefits. However, the high cost associated with using over 13–20 mg/Wp of Ag can impede the development of truly cost‐effective solar cells. Therefore, there is an urgent need to explore alternative, economically viable metals compatible with silicon substrates. This study reports on the application of a contact stack consisting of Ag, nickel (Ni), and copper (Cu) in Si solar cells. To prevent Schottky contact formation, Ag is implemented as a seed layer, whereas Ni and Cu form the metal bulk layer. The fabricated bi‐layer stack without selective emitter exhibits a maximum efficiency of ~21.5%, a fill factor of 81.5%, and an average contact resistance of 5.88 mΩ·cm2 for a monofacial PERC cell. Microstructure analysis demonstrates that the metals within the contacts remain distinct, and Cu diffusion into the silicon during the firing process is absent. Consequently, printed bi‐layer contacts emerge as a promising alternative to Ag contacts, reducing the Ag consumption to below 2.5 mg/Wp per cell without compromising overall efficiency. [ABSTRACT FROM AUTHOR]

Flexible, breathable, and highly sensitive pressure sensors have increasingly become a focal point of interest due to their pivotal role in healthcare monitoring, advanced electronic skin applications, and disease diagnosis. However, traditional methods, involving elastomer film‐based substrates or encapsulation techniques, often fall short due to mechanical mismatches, discomfort, lack of breathability, and limitations in sensing abilities. Consequently, there is a pressing need, yet it remains a significant challenge to create pressure sensors that are not only highly breathable, flexible, and comfortable but also sensitive, durable, and biocompatible. Herein, we present a biocompatible and breathable fabric‐based pressure sensor, using nonwoven fabrics as both the sensing electrode (coated with MXene/poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate [PEDOT:PSS]) and the interdigitated electrode (printed with MXene pattern) via a scalable spray‐coating and screen‐coating technique. The resultant device exhibits commendable air permeability, biocompatibility, and pressure sensing performance, including a remarkable sensitivity (754.5 kPa−1), rapid response/recovery time (180/110 ms), and robust cycling stability. Furthermore, the integration of PEDOT:PSS plays a crucial role in protecting the MXene nanosheets from oxidation, significantly enhancing the device's long‐term durability. These outstanding features make this sensor highly suitable for applications in full‐range human activities detection and disease diagnosis. Our study underscores the promising future of flexible pressure sensors in the realm of intelligent wearable electronics, setting a new benchmark for the industry. [ABSTRACT FROM AUTHOR]

In the age of data science, voice data can be treated as one of the crucial assets used for strengthening biometrics technologies and biomedical applications. However, voice biometrics is still at emergence state facing voice variability, cross‐linguistic variations, and voice spoofing challenges. These long‐standing issues are proposed to be solved by deploying an organic, flexible, and printed piezoelectric polymeric interface exhibiting several unique features such as strong directionality, stability over a large operating temperature range (30–90 ˚C), broad frequency (6 kHz), ultra sensitivity (5.77 V Pa−1) and high signal‐to‐noise ratio (38–55 dB). By analyzing speech processing parameters acquired by the voice sensor, an individual voiceprint is established, which is further utilized to train a neural network model for deploying artificial intelligence (AI)‐driven voice biometrics, resulting in a remarkable accuracy of >96% for population identification and speaker recognition and >93% for healthcare assessment. Featuring a versatile printing fabrication process, innovative voiceprint approach, and a robust neural network, the programmable polymeric acoustic interface proposes a promising complementary tool to the existing biometrics technologies and plays a vital role in healthcare monitoring. [ABSTRACT FROM AUTHOR]

Herein, new insights into the printability, rheological, morphological, dielectric, and piezoelectric characteristics of microscale thick-film particulate ferroelectric composites are provided. This is achieved by the fabrication and printing of diethylene glycol monoethyl ether acetate (DGMEA)/DI7025/barium titanate (BaTiO3) inks with varying filler content. The effects of DGMEA and BaTiO3 microparticles on the rheological response are investigated using shear, stress frequency dependence, and three-part recovery tests. The structural and morphological characteristics are analyzed using Fourier-transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. The functional sensing behavior is investigated through impedance spectroscopy, piezoelectric, and ferroelectric experiments. The dependences of the dielectric and piezoelectric properties of the composites on BaTiO3 volume fraction are reported and analyzed in terms of Yamada model. The best performance is obtained from the composites with 40 vol% BaTiO3 with parallel-layered structured connectivity. The results offer important insights for the future development of new and improved thin film sensors. [ABSTRACT FROM AUTHOR]

Electrochemical‐based memristors are highly attractive that are capable of nonvolatile analog tuning, long‐term state stability, low power consumption, device scalability, and fast switching speeds. Through the combination of film deposition techniques, i.e., vapor phase polymerization and screen printing, fabrication of a poly(4‐(6‐hexyl)‐4H‐dithieno[3,2‐b:2′,3′‐d]pyrrole) (p6DTP)‐based synaptic‐emulating three‐terminal memristor is designed. Through voltage‐driven pulse programming, and square waves with an amplitude of 100 mV and duration of 100 msec, the device exhibits a power consumption of 1 pJmm−2 per synaptic event. By analyzing the fundamental operational trends of the p6DTP‐based device, simple and advanced integrated applications can be demonstrated along with synaptic‐like responses. This effort is the first presentation of the vapor phase polymerization technique for any dithienopyrrole‐based monomers, along with the physical implementation of any memristive system as an advanced logical circuit, demonstrated here as a cascaded combinational logic gate. [ABSTRACT FROM AUTHOR]

The fabrication of a fully printed, lead‐free, polymer piezoelectric transducer is presented and the characterization of its structural, dielectric, and ferroelectric properties at different processing stages is demonstrated. The performance of poly(vinylidene fluoride‐trifluoroethylene) transducers with resonance frequency analyses, acoustic power measurements, and pulse‐echo experiments is evaluated. Notably, for the first time for a fully printed transducer, an optimal performance in the medical ultrasound range (<15 MHz) is demonstrated with acoustic power >1 W cm−2, which is promising for applications in epidermal and wearable electronics. Overall, the findings provide a strong foundation for future research in the area of flexible ultrasound transducers. [ABSTRACT FROM AUTHOR]

Displays are one of the most mature technologies in the field of printed electronics. Their ability to be manufactured in large quantities and at low cost has led to their recent uptake into the consumer market. Within this article this technology is extended to electrochromic display stickers. This is achieved using a recent reverse display architecture screen printed on textile and paper sticker substrates. The electrochromic stickers are comparable to plastic control substrates and show little performance difference even when adhered to curved surfaces. The electrochromic display technology is extended to sticker labels for authentication applications by patterning either the dielectric or the graphical layer. A proof‐of‐concept prototype emulating a wax seal on an envelope is presented to show that other colors can be implemented in this technology. [ABSTRACT FROM AUTHOR]

Stretchable organic electrochemical transistors (OECTs) are promising for wearable applications within biosensing, bio‐signal recording, and addressing circuitry. Efficient large‐scale fabrication of OECTs can be performed with printing methods but to date there are no reports on high‐performance fully printed stretchable OECTs. Herein, this challenge is addressed by developing fully screen‐printed stretchable OECTs based on an architecture that minimizes electrochemical side reactions and improves long‐term stability. Fabrication of the OECTs is enabled by in‐house development of three stretchable functional screen‐printing inks and related printing processes. The stretchable OECTs show good characteristics in terms of transfer curves, output characteristics, and transient response up to 100% static strain and 500 strain cycles at 25% and 50% strain. The strain insensitivity of the OECTs can be further improved by strain conditioning, resulting in stable performance up to 50% strain. Finally, an electrochromic smart pixel is demonstrated by connecting a stretchable OECT to a stretchable electrochromic display. It is believed that the development of screen‐printed stretchable electrochemical devices, and OECTs in particular, will pave the way for their use in wearable applications and commercial products. [ABSTRACT FROM AUTHOR]

Printing technologies have emerged as a viable method for the fabrication of various electronic components, including sensors, actuators, energy harvesters, thin-film transistors and circuits, as well as antennas. However, printing processes have limitations in terms of surface roughness and thickness. Printing conductive structures on novel substrates, such as cellulose-based sustainable paper, also leads to further challenges linked to the high surface porosity and ink carrier absorption. Herein, the variability of paper-based printed antenna performance due to different printing processes, ink carrier absorption, and temperature is investigated. The resonance frequency and gain of different printed antennas (e.g., screen, inkjet, and dispense-printed) are compared in terms of surface roughness, thickness, and resonance frequency. Screen-printed antennas show better performance compared to other printed antennas. The results show that the resonance frequency of antenna shifts 20, 30, and 50 MHz for screen printed, dispense printed, and inkjet printed respectively, from the nominal 2.6 GHz. In the case of the inkjet-printed antenna, a clear effect of skin depth is observed, due to the 0.91 μm thickness. Furthermore, it is demonstrated that the permittivity/dielectric constant of the paper substrate is significantly influenced by ink carrier absorption and temperature variance. [ABSTRACT FROM AUTHOR]

Systems for wireless energy transmission (WET) are gaining prominence nowadays. This work presents a WET system based on the photo‐thermoelectric effect. With an incident laser beam at λ = 1450 nm, a temperature gradient is generated in the radial flexible thermoelectric (TE) device, with a carbon‐based light collector in its center to enhance the photoheating. The three‐part prototype presents a unique approach by using a radial TE device with one simple manufacturing process ‐ screen‐printing. A TE ink with a polymeric matrix of poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate and doped‐Poly(vinyl alcohol) with Sb‐Bi‐Te microparticles is developed (S∽33 µVK−1 and s∽10.31 Sm−1), presenting mechanical and electrical stability. Regarding the device, a full electrical analysis is performed, and the influence of the light collector is investigated using thermal tests, spectrophotometry, and numerical simulations. A maximum output voltage (Vout) of ∽16 mV and maximum power density of ∽25 µWm−2 are achieved with Plaser = 2 W. Moreover, the device's viability under extreme conditions is explored. At T∽180 K, a 25% increase in Vout compared to room‐temperature conditions is achieved, and at low pressures (∽10‒6 Torr), an increase of 230% is obtained. Overall, this prototype allows the supply of energy at long distances and remote places, especially for space exploration. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive overview on printing technologies for metallization of solar cells. Throughout the last 30 years, flatbed screen printing has established itself as the predominant metallization process for the mass production of silicon solar cells. For this reason, we will provide a detailed review on its history, its evolution over time, and how the continuous efforts of the scientific and industrial community for further improvements revolutionized the entire PV industry. Furthermore, we will guide the reader through the physics on silicon solar cell metallization, the fundamentals on contact formation, and what type of challenges and requirements these topics create for printing technologies. The main topic of this review addresses the flatbed screen‐printing process mechanics, its different process sequences, corresponding screen technology, and the very important impact of paste rheology on the printing result. Finally, we will compare alternative upcoming printing approaches to flatbed screen printing and discuss how they might solve upcoming challenges in metallization in terms of increasing the throughput rates at an ever‐decreasing grid line width and reduced silver consumption. [ABSTRACT FROM AUTHOR]

Breathable, flexible, and highly sensitive pressure sensors have drawn increasing attention due to their potential in wearable electronics for body‐motion monitoring, human‐machine interfaces, etc. However, current pressure sensors are usually assembled with polymer substrates or encapsulation layers, thus causing discomfort during wearing (i.e., low air/vapor permeability, mechanical mismatch) and restricting their applications. A breathable and flexible pressure sensor is reported with nonwoven fabrics as both the electrode (printed with MXene interdigitated electrode) and sensing (coated with MXene/silver nanowires) layers via a scalable screen‐printing approach. Benefiting from the multi‐layered porous structure, the sensor demonstrates good air permeability with high sensitivity (770.86–1434.89 kPa−1), a wide sensing range (0–100 kPa), fast response/recovery time (70/81 ms), and low detection limit (≈1 Pa). Particularly, this sensor can detect full‐scale human motion (i.e., small‐scale pulse beating and large‐scale walking/running) with high sensitivity, excellent cycling stability, and puncture resistance. Additionally, the sensing layer of the pressure sensor also displays superior sensitivity to humidity changes, which is verified by successfully monitoring human breathing and spoken words while wearing a sensor‐embedded mask. Given the outstanding features, this breathable sensor shows promise in the wearable electronic field for body health monitoring, sports activity detection, and disease diagnosis. [ABSTRACT FROM AUTHOR]

Novel thermochromic and vapochromic paper substrates were prepared via screen printing with anthocyanin extract in the presence of ferrous sulfate mordant, resulting in multi‐stimuli responsive colorimetric paper sheets. Environmentally friendly anthocyanin extract was obtained from red‐cabbage (Brassica oleracea var. capitata L.) to function as spectroscopic probe in coordination with ferrous sulfate mordant. Pink anthocyanin/resin nanocomposite films immobilized onto paper surface were developed by well‐dispersion of anthocyanin extract as a colorimetric probe in a binding agent without agglomeration. As demonstrated by CIE colorimetric studies, the pink (λmax = 418 nm) film deposited onto paper surface turns greenish‐yellow (λmax = 552 nm) upon heating from 25 to 75°C, demonstrating new thermochromic film for anti‐counterfeiting applications. The thermochromic effects were investigated at different concentrations of the anthocyanin extract. Upon exposure to ammonia gas, the color of the anthocyanin‐printed sheets changes rapidly from pink to greenish‐yellow, and then immediately returns to pink after taking the gaseous ammonia stimulus away, demonstrating vapochromic effect. The current sensor strip showed a detection limit for ammonia gas in the range 50–300 ppm. Both thermochromism and vapochromism showed high reversibility without fatigue. In addition to studying the rheological properties of the prepared composites, the morphological and mechanical properties of the printed cellulose substrates were also studied. [ABSTRACT FROM AUTHOR]

The development of fast‐charging technologies is crucial for expediting the progress and promotion of electric vehicles. In addition to innovative material exploration, reduction in the tortuosity of electrodes is a favored strategy to enhance the fast‐charging capability of lithium‐ion batteries by optimizing the ion‐transfer kinetics. To realize the industrialization of low‐tortuosity electrodes, a facile, cost‐effective, highly controlled, and high‐output continuous additive manufacturing roll‐to‐roll screen printing technology is proposed to render customized vertical channels within electrodes. Extremely precise vertical channels are fabricated by applying the as‐developed inks, using LiNi0.6Mn0.2Co0.2O2 as the cathode material. Additionally, the relationship between the electrochemical properties and architecture of the channels, including the pattern, channel diameter, and edge distance between channels, is revealed. The optimized screen‐printed electrode exhibited a seven‐fold higher charge capacity (72 mAh g−1) at a current rate of 6 C and superior stability compared with that of the conventional bar‐coated electrode (10 mAh g−1, 6 C) at a mass loading of 10 mg cm−2. This roll‐to‐roll additive manufacturing can potentially be applied to various active materials printing to reduce electrode tortuosity and enable fast charging in battery manufacturing. [ABSTRACT FROM AUTHOR]

Flexible and reconfigurable (FAR) electronics are in high demand for emerging applications, including wearable, bioelectronics, and internet of things. Highly scalable antenna arrays or periodic surfaces are required for high directivity or electromagnetic wave path control, particularly for 5G millimeter‐wave (mm‐wave) due to high path losses. Conventional lumped tuning components have limitations related to scalable FAR electronics and hence highly scalable and flexible vanadium dioxides (VO2) switch array is proposed for mm‐wave applications. A frequency reconfigurable mm‐wave absorber is designed by screen printing the VO2 switch array to demonstrate the proposed approach feasibility for large scale electronics, achieving high scalability, tunability, and flexibility because the 40 µm thick VO2 switch array satisfies radio frequency switch requirement. Flexibility and repeatability are tested up to 2000 bending cycles with 25 mm bending radius, and tunability and scalability are demonstrated with 300 ON/OFF ratio, and 98% product yield for 400 switches printed on 144 × 144 mm2 polyethylene terephthalate substrates. Absorption frequency is switchable from 14 to 28 GHz at 150 mm bend radius while retaining better than 90% absorptivity as a frequency reconfigurable mm‐wave absorber. Therefore, the proposed VO2 switch array would be suitable for scalable 5G and 6G FAR electronics. [ABSTRACT FROM AUTHOR]

The development and preparation process of a flexible MiniLED line subgrade board on a white reflective sheet was carried out in this paper using silk‐printing nanoscale silver paste assisted bonding technology. The design of the line conductivity parameter ‐ nanoscale silver paste parameter model, printing plate selection, and process verification were systematically completed, as well as the preparation and reliability confirmation of flexible MiniLED lamp board. The flexible MiniLED lamp board with disposable sintered nano silver slurry lines was successfully prepared, and the 65" backlight module was constructed. [ABSTRACT FROM AUTHOR]

Hydraulic pressing and screen printing methods are used to create particulate magnetoelectric composites and laminated trilayered thick‐film composites. X‐ray diffraction studies reveal the presence of cubic spinel and tetragonal perovskite structures for individual powders of ferrite CuFe2O4 and ferroelectric‐phase PbZr0.58Ti0.42O3. The dielectric constant of particulate composites decreases with increasing frequency around 1 MHz and beyond that frequency, a saturation state is attained. However, for laminated films, the dielectric constant decreases up to 1 MHz and then increases. The maximum dielectric constant at low frequency for particulate CuFe2O4/PZT composites is around 72.2, whereas for laminated CuFe2O4/PZT/CuFe2O4 composites it is 4.97 and for PZT/CuFe2O4/PZT composites is 5.24. Loss tangent exhibits the same trend as dielectric constant with frequency, which is explained by space charge polarization and is consistent with Koop's phenomenological theory. The dielectric constant's variation with temperature describes the contribution of electric dipoles to polarization and both composites exhibit absorption peaks. The semiconducting nature of both particulate and laminated composites can be seen in the DC resistivity graph with frequency and as frequency increases, DC resistivity decreases for both composites, which is explained by the small polaron‐hopping phenomenon. The magnetoelectric coupling effect for particulate composites (44 mV Oe−1cm−1) is also found to be small when compared to laminated trilayered composites (CuFe2O4/PZT/CuFe2O4—105 mV Oe−1cm−1 and PZT/CuFe2O4/PZT—68 mV Oe−1cm−1). [ABSTRACT FROM AUTHOR]

Quantum dots (QDs) are one kind of photoluminescent materials with excellent properties, such as adjustable spectrum, narrow full width at half maximum (FWHM), and high color gamut. In this paper, a photoluminescent QDs printing paste suitable for light guide dots array applied in the backlight for liquid crystal display (LCD) was presented. The QDs printing paste was first prepared and characterized with different kinds of solvents. Then, triphenyl phosphite (TPP), a kind of antioxygen, was added into the QDs printing paste to improve the stability of the QDs printing paste. Finally, a QDs light guide plate (LGP) was fabricated by screen printing with QDs printing paste added with silicon dioxide (SiO2) light scattering particles. The color gamut of QDs LGP arrived 131.6%NTSC due to light scattering interaction between blue LED, red QDs, green QDs, and SiO2 particles. The results showed that the QDs‐chloroform printing paste had uniform light output and the highest photoluminescent peak intensity. Therefore, the composite screen printing paste has wide application prospects in the backlight of LCD, with the advantages of simple process, high production efficiency, and low cost. [ABSTRACT FROM AUTHOR]

The development of batch fabrication techniques for flexible skin patches may promote the use of these devices in daily health monitoring and public health crisis. Here, a modularized mass fabrication and selective integration approach that can yield multiparameter electronic skin patches are presented. The screen‐printing technique has been adopted to achieve five modularized sensors for electrocardiogram (ECG), temperature, hydration, blood oxygen, and pH sensing as well as a universal central hub to connect the sensors with external wireless circuits. In a single glass substrate, 13 ECG electrodes, more than 200 sensors, or 80 central hubs can be printed with high homogeneity in performance. In addition to rapid printing of these components, special temperature‐sensitive paste, batch electropolymerization processes, selection of stress confining substrates, and usage of anisotropic conductive tapes have been investigated to facilitate the integration processes of the multiparameter skin patches. The systematic techniques presented in this paper may help to overcome the bottleneck that is currently constraining the mass fabrication of multiparameter skin patches, allowing rapid deployment and convenient application of these devices for health monitoring in large populations. [ABSTRACT FROM AUTHOR]

Low‐cost, flexible and thin display technology is becoming an interesting field of research as it can accompany the wide range of sensors being developed. Here, the synthesis of poly(dimethylpropylene‐dioxythiophene) (PProDOT‐Me2) by combining vapor phase polymerization and screen printing is presented. A multilayer architecture using poly(3,4‐ethylenedioxythiophene) (PEDOT) and PProDOT‐Me2 to allow for electrochromic switching of PProDOT‐Me2, thereby eliminating the need for a supporting transparent conductive (metal oxide) layer is introduced. Furthermore, the technology is adapted to a blended architecture, which removes the additional processing steps and results in improved color contrast (∆E* > 25). This blend architecture is extended to other conductive polymers, such as PEDOT and polypyrrole (PPy), to highlight the ability of the technique to adjust the color of all‐printed electrochromic displays. As a result, a green color is obtained when combining the blue and yellow states of PEDOT and PPy, respectively. This technology has the potential to pave the way for all‐printed multicolored electrochromic displays for further utilization in printed electronic systems in various Internet of Things applications. [ABSTRACT FROM AUTHOR]

The high usage of silver in industrial solar cells may limit the growth of the solar industry. One solution is to replace Ag with copper. A screen printable Cu paste is used herein to metallize industrial interdigitated back contact (IBC) solar cells. A novel metallization structure is proposed for making solar cells. Cu paste is applied to replace the majority of the Ag used in IBC cells as busbars and fingers. Cu paste is evaluated for use as fingers, and solar cells are made to test conversion efficiency and reliability. The Cu paste achieves comparably low resistivity, and Cu paste printed cells demonstrate similar efficiency to Ag paste printed cells, with an average efficiency of 23%, and only 4.5 mg W−1 of Ag usage. Also, the solar cells are stable and no Cu in‐diffusion is observed under damp heat (85 °C, 85% relative humidity) and thermal stress (200 °C) for 1000 h, respectively. All processes used in this study can be carried out with industrial equipment. These findings reveal a new application for Cu pastes and point to a new direction for reducing Ag utilization and cost. [ABSTRACT FROM AUTHOR]

Using cost‐effective fabrication methods to manufacture a high‐performance solid oxide fuel cell (SOFC) is helpful to enhance the commercial viability. Here, we report an anode‐supported SOFC with a three‐layer Gd0.1Ce0.9O1.95 (gadolinia‐doped‐ceria [GDC])/Y0.148Zr0.852O1.926 (8YSZ)/GDC electrolyte system. The first dense GDC electrolyte is fabricated by co‐sintering a thin, screen‐printed GDC layer with the anode support (NiO–8YSZ substrate and NiO–GDC anode) at 1400°C for 5 h. Subsequently, two electrolyte layers are deposited via physical vapor deposition. The total electrolyte thickness is less than 5 μm in an area of 5 × 5 cm2, enabling an area‐specific ohmic resistance as low as 0.125 Ω cm−2 at 500°C (under open circuit voltage), and contributing to a power density as high as 1.2 W cm−2 at 650°C (at an operating cell voltage of 0.7 V, using humidified [10 vol.% H2O] H2 as fuel and air as oxidant). This work provides an effective strategy and shows the great potential of using GDC as an electrolyte for high‐performance SOFC at intermediate temperature. [ABSTRACT FROM AUTHOR]

One of the main challenges for the industrialization of the passivating contact approach for Si solar cells is the metallization with screen‐printed paste while maintaining the low saturation current density. Using a non‐commercial Ag paste to metallize atmospheric pressure chemical vapor deposition (APCVD) (n) poly‐Si, the metal contact formation for passivating contacts on planar and textured substrates is investigated. The paste creates deep imprints caused by silver crystallite formation at the pyramid tips of textured silicon wafers. In contrast, on planar wafers, the silver crystallite growth stops at the interface between poly‐Si and the Si wafer. Similar contact resistivities are determined by comparing textured and planar Si samples. On planar samples, a contact resistivity of 4.6(14) mΩcm2 and a saturation current density of only 141(10) fA cm−2 for the metallized contact area are demonstrated. Textured samples with a contact resistivity of 2.7(17) mΩcm2 show a higher saturation current of 480(40) fA cm−2. This etching behavior is investigated by structural and elemental analyses using scanning electron microscopy. [ABSTRACT FROM AUTHOR]

The development of conformable electronic systems' focuses on the multifunctional smart materials transform areas from the automotive industry to biomedicine, based on improved integration and advanced functionalities. In‐mold electronics (IME) combines thermoforming, injection molding, and printed electronics, resulting in sensing structural parts integrated into smart surfaces, communicating with computer systems, and enabling advanced experiences in terms of human‐machine interaction. Contrary to flexible electronics, designed as bend conductors around a single axis, thermoformed electronics allow deformations in the three‐axial directions for different geometries. Herein, a 2D screen‐printed pattern using conductive silver ink thermoformed into a spherical surface suitable for 3D gesture recognition is reported. The mechanical deformation of the high‐impact polystyrene sheet (HIPS) and polyethylene terephthalate‐glycol (PETG) substrates during the thermoforming process of the electrical circuit is characterized experimentally. The electrical resistance changes through the circuit in the stages of the fabrication process due the thickness decrease and the propagation of the small cracks. Both evaluations contribute to a better understanding of the performance of the materials when subject to the IME process. Validation of the 3D gesture recognition operation is carried out, demonstrating their full operability, as well as the possibilities that the combination of technologies allows. [ABSTRACT FROM AUTHOR]

The multilayer triboelectric nanogenerators (TENGs) are widely developed to enhance the output performance of device. However, these TENGs consisting of electron transfer, transport, trap layers toward a large volumetric charge density should be wearable and mass‐produced for commercialization. Thus, appropriate material selection in respective layers and fabrication method are crucial for the commercialization of multilayer TENG. This study presents all‐printed, sustainable wearable TENGs based on electron accumulation polymers (EAPs) with superior charge retention capability. The EAPs consisting of polytetrafluoroethylene (PTFE), carboxyl functionalized single‐walled carbon nanotubes (SWCNTs:COOH), and Ti3C2Tx (MXene) in a fluorinated polymer matrix, are used. Compared to the reference, the EAPs not only lead to approximately six times higher output performance (300 V and 40 µA) but also four times more sustainable charge retention capability (92%) for an hour. These are attributed to the three‐step electron‐trapping mechanism with electron transfer/transport from PTFE/SWCNT and electron trapping in MXene. In addition, TENGs with EAPs exhibit excellent mechanical stability and reliability with fascinating single‐electrode demonstrations. Finally, the TENG with EAPs can efficiently operate various portable electronics and pH monitoring systems with a pH sensor and a seven‐segment display in realistic scenarios. [ABSTRACT FROM AUTHOR]

Screen printed piezoelectric polyvinylidene fluoride–trifluoro ethylene (PVDF–TrFE)‐based sensors laminated between glass panes in the temperature range 80–110 °C are presented. No degradation of the piezoelectric signals is observed for the sensors laminated at 110 °C, despite approaching the Curie temperature of the piezoelectric material. The piezoelectric sensors, here monitoring force impact in smart glass applications, are characterized by using a calibrated impact hammer system and standardized impact situations. Stand‐alone piezoelectric sensors and piezoelectric sensors integrated on poly(methyl methacrylate) are also evaluated. The piezoelectric constants obtained from the measurements of the nonintegrated piezoelectric sensors are in good agreement with the literature. The piezoelectric sensor response is measured by using either physical electrical contacts between the piezoelectric sensors and the readout electronics, or wirelessly via both noncontact capacitive coupling and Bluetooth low‐energy radio link. The developed sensor concept is finally demonstrated in smart window prototypes, in which integrated piezoelectric sensors are used to detect break‐in attempts. Additionally, each prototype includes an electrochromic film to control the light transmittance of the window, a screen printed electrochromic display for status indications and wireless communication with an external server, and a holistic approach of hybrid printed electronic systems targeting smart multifunctional glass applications. [ABSTRACT FROM AUTHOR]

Carbon‐based perovskite solar cells (C‐PSCs) have attracted worldwide attention in the research community due to their low‐cost fabrication and improved stability compared with conventional PSCs. However, the cell reproducibility and inconsistency of perovskite infiltration into micrometer‐thick mesoscopic devices remain an issue for cell fabrication. Furthermore, full perovskite crystallization in the screen‐printed device without any perovskite formed on the mesoporous carbon electrode is always challenging. The presence of protruding perovskite crystals on C‐PSCs is found, which initially leads to the hydrolysis of perovskites under humid condition and eventually accelerates the degradation. Herein, a low‐temperature (low‐T) carbon layer is incorporated through a scalable screen‐printing technique on top of C‐PSCs. C‐PSCs coated with low‐T carbon show good moisture (70% relative humidity) and thermal (65 and 85 °C) stability over 3,250 and 1,000 h, respectively, without any physical encapsulation. The device also shows high stability under continuous illumination at its maximum power point for 175 h. This hydrophobic and conductive carbon layer not only protects the exposed perovskite crystals from moisture but also enhances the photovoltaic performance of C‐PSCs with major fill factor and open‐circuit voltage improvement. [ABSTRACT FROM AUTHOR]

Screen printing has received significant attention for manufacturing energy storage devices. However, preparing high‐quality inks is still one of the main challenges. Herein, a homogenous and stable ink based on the monoclinic phase of VO2(M) microparticles has been synthesized by a simple hydrothermal process in only 6 h and through nontoxic solutions. The VO2 ink is printed on Kapton substrate in a single‐layer as well as in a double‐layer arrangement (1‐LP and 2‐LP). The printed 1‐LP VO2 electrode delivers a maximum areal capacitance of 20 mF cm−2 with a small equivalent series resistance of 4 Ω without conducting additives. The interdigitated full‐cell VO2 supercapacitor adequately employs the electric double‐layer and Faradic redox mechanisms in 1.4 V, which is the highest operating voltage reported for symmetric supercapacitors based on pure vanadium oxide electrodes in aqueous inorganic electrolytes. Moreover, the maximum areal energy of the 2‐LP supercapacitor is 0.8 μWh cm−2 at an areal power of 21.0 μW cm−2, which is larger than the 1‐LP (0.2 μWh cm−2 at 17.5 μW cm−2). This improvement is attributed to the homogenously printed double layer of the porous VO2 microparticles. Integrating such supercapacitors into thin‐film electronics could develop portable devices. [ABSTRACT FROM AUTHOR]

Flexible strain sensors have attracted intense interest due to their application as intelligent wearable electronic devices. However, it is still a huge challenge to achieve a flexible sensor with simultaneous high sensitivity, excellent durability, and a wide sensing region. In this work, a crack‐based strain sensor with a paired‐serpentine conductive network is fabricated onto flexible film by screen printing. The innovative conductive network exhibits a controlled crack morphology during stretching, which endows the prepared sensor with outstanding sensing characteristics, including high sensitivity (gauge factor up to 2391.5), wide detection (rang up to 132%), low strain detection limit, a fast response time (about 40 ms), as well as excellent durability (more than 2000 stretching/releasing cycles). Benefiting from these excellent performances, full‐range human body motions including subtle physiological signals and large motions are accurately detected by the prepared sensor. Furthermore, wearable electronic equipment integrated with a wireless transmitter and the prepared strain sensor shows great potential for remote motion monitoring and intelligent mobile diagnosis for humans. This work provides an effective strategy for the fabrication of novel strain sensors with highly comprehensive performance. [ABSTRACT FROM AUTHOR]

This work demonstrates a novel fabrication approach based on the combination of screen and aerosol jet printing to manufacture fully printed organic electrochemical transistors (OECTs) and OECT‐based logic circuits on PET substrates with superior performances. The use of aerosol jet printing allows for a reduction of the channel width to ≈15 µm and the estimated volume by a factor of ≈40, compared to the fully screen printed OECTs. Hence, the OECT devices and OECT‐based logic circuits fabricated with the proposed approach emerge with a high ON/OFF ratio (103–104) and remarkably fast switching response, reaching an ON/OFF ratio of >103 in 4–8 ms, which is further demonstrated by a propagation delay time of just above 1 ms in OECT‐based logic inverter circuits operated at a frequency of 100 Hz. All‐printed monolithically integrated OECT‐based five‐stage ring oscillator circuits further validated the concept with a resulting self‐oscillation frequency of 60 Hz. [ABSTRACT FROM AUTHOR]

Smart label technology such as indicators is a growing field due to society's demand for Internet of Things devices. New materials and technologies are continuously being discovered and developed in order to provide better resolution, better performance, or more environmentally friendly devices. Within this report, screen printing technology is combined with vapor phase polymerization to synthesize three conductive polymers; poly(3,4‐ethylenedioxythiophene) (PEDOT), polypyrrole (PPy), and polythiophene (PTh). The conductive polymers are created in micrometer resolution and investigated for their electrochromic properties. PEDOT and PPy samples are combined into printed, laminated, transmissive electrochromic displays. The technology is further advanced to establish separate PEDOT, PPy, and PTh all‐printed electrochromic displays using several screen printed layers. The PEDOT displays show improved color retention as compared to displays created with commercially available PEDOT:poly(styrene sulfonate) (PSS) with comparable contrast and switching behavior. All‐printed PPy and PTh electrochromic displays with impressive electrochromic behavior are demonstrated. More complex patterns of 7‐segment displays are created, thereby highlighting flexibility and individually switched sections of the conductive polymers. This research extends the screen printing and vapor phase polymerization combination to other conductive polymers and the potential commercialization of multicolor electrochromic displays that has been otherwise dominated by monochromatic PEDOT:PSS. [ABSTRACT FROM AUTHOR]

The impact of the phosphorus doping density in direct current‐sputtered polysilicon layers on surface passivation and contact resistance by fabricating polysilicon on oxide (POLO) contacts is studied, when applying doping densities ranging from 3 × 1019 to 4 × 1020 cm−3. Hydrogenation is performed either via a hydrogen‐releasing AlOx layer and postdeposition anneals in forming gas using a tube furnace at 400 °C, or by rapid firing of an AlOx/SiNy stack in a conveyor belt furnace at 810 °C. The study shows that the forming gas anneal of the weakly in situ phosphorus‐doped poly‐Si layers with AlOx enables a passivation quality with an implied open‐circuit voltage of up to 734 mV and a recombination current density down to 1.8 fA cm−2. For fast firing, a high phosphorus concentration of 4 × 1020 cm−3 is required for comparably high passivation quality with a recombination current density down to 1.3 fA cm−2. A p‐type POLO back‐junction solar cell featuring such ex situ doped sputtered POLO contacts with a cell efficiency of 22.4% and an open‐circuit voltage of 714 mV is fabricated. To our knowledge, this is the highest open‐circuit voltage published so far with sputtered POLO contacts. [ABSTRACT FROM AUTHOR]

With the rapid advances in wearable technology, several excellent strain sensors have been developed. Recent strain sensors have met various requirements, such as mechanical applicability, rapid responsiveness, and high sensitivity. Nevertheless, the processing technology, wearing comfort, and safety of strain sensors, which have received inadequate attention, have greatly hindered their commercial development and large‐scale use. Through mature electrospinning and screen‐printing, a high‐performance, safe, comfortable, waterproof, breathable, economical, and reliable wearable strain sensor is simply and quickly prepared. This strain sensor has excellent repeatability and stability with remarkable sensitivity (maximum gauge factor = 520), a broad working strain range (500%), and an ultrafast response time (100 ms). Notably, the mechanical properties of the proposed strain sensor are similar to those of natural skin, making the sensor a good match to the skin. Additionally, the strain sensor has incomparable biofriendly, enabling long‐term harmless contact with the skin. To the best of the authors' knowledge, this is the first report on the optimization of flexible electronic equipment in terms of the manufacturing process, sensing performance, and wearing experience. The results of this study have important implications for the development and practical application of flexible electronics. [ABSTRACT FROM AUTHOR]

Large area manufacturing of printed electronic components on ~A4‐sized substrates is demonstrated by the combination of screen printing and vapor phase polymerization (VPP) into poly(3,4‐ethylenedioxythiophene) (PEDOT). The oxidant layer required for the polymerization process is screen printed, and the resulting conductive polymer patterns are manufactured at high resolution (100 µm). Successful processing of several common oxidant species is demonstrated, and the thickness can be adjusted by altering the polymerization time. By comparing the polymer films of this work to a commercial PEDOT:PSS (PEDOT doped with poly(styrene sulfonate)) screen printing ink shows improved surface roughness (26 vs 69 nm), higher conductivity (500 vs 100 S cm–1) and better resolution (100 vs 200 µm). Organic electrochemical transistors, in which the transistor channel is polymerized into PEDOT through VPP, are also demonstrated to further emphasize on the applicability of this manufacturing approach. The resulting transistor devices are not only functional, they also show remarkable switching behavior with respect to ON current levels (–70 mA at –1 V), ON/OFF ratios (>105), switching times (tens of ms) and transconductance values (>100 mS) in standalone transistor devices, in addition to a high amplification factor (>30) upon integration into a screen printed inverter circuit. [ABSTRACT FROM AUTHOR]

Fabrication of large‐area transparent conducting electrodes (TCEs) of high performance through cost‐effective high throughput methods has been an area of intensive research. In this context, the fabrication of flexible, 25 cm2 wide TCEs with high figure of merit (FoM) (≈494 Ω−1) is achieved by two roll‐to‐roll compatible processes, namely screen printing and spray coating, by suitably modifying crackle lithography in a cost‐effective manner. The fabricated TCEs exhibit low sheet resistance (<10 Ω □−1) and high transmittance (≈86–90%) in the visible region. The TCEs are shown to be highly bendable, the change in the sheet resistance is only ≈2% up on 6000 bending cycles. The application of these TCEs as transparent bendable uniform Joule heaters and surface capacitive touchscreens has also been demonstrated. The TCEs are, thus, just as good as any TCE produced using spin‐coating or similar small area coating techniques. [ABSTRACT FROM AUTHOR]

The development of polymer‐based conductive inks has gained increasing interest in the areas of printed and molded electronics. Graphene‐based materials are explored in this scope, reduced graphene oxide (rGO) being among the most used conductive filler components of the inks. Herein, rGO is doped with nitrogen to obtain N‐rGO; the replacement of oxygen atoms by nitrogen ones increases the electrical conductivity of graphene. Polymer‐based conductive inks reinforced with graphene are developed based on polyvinylpyrrolidone (PVP) as polymer binder and dihydrolevoglucosenone (Cyrene) as solvent, leading thus to environmentally friendly conductive inks. Screen‐printable inks are optimized in terms of viscosity and adhesion properties, leading to printed films with sheet resistance close to Rs = 1 kΩ sq−1, the graphene:PVP inks being also biocompatible and nontoxic. [ABSTRACT FROM AUTHOR]

Passivated contact based on a thin interfacial oxide and a highly doped polysilicon layer has emerged as the next evolutionary step to increase the efficiencies of industrial silicon solar cells. To take maximum advantage from this layer stack, it is vital to limit the losses at the metal polysilicon interface, which can be quantified as metal polysilicon recombination current density (J0met) and contact resistivity. In cell concepts, wherein a large variety of silicon substrate surface finish can be obtained, it is essential to know how the surface finish affects the J0met and contact resistivity. Herein, commercially available fire through silver paste and the metal‐polysilicon recombination current densities and contact resistivity are used for three different silicon substrate surface finishes, namely: planar or saw damage etched (SDE), chemically polished in acidic solution and alkaline pyramidal textured. Contact resistivity values below 3 mΩ cm2 with J0met in order of the recombination current density of the doped region (J0pass) are obtained for samples with planar surface for both 150 and 200 nm n+ polysilicon layer thicknesses. The results presented in this work show that the samples with flat substrate morphology outperform the samples with textured surfaces. [ABSTRACT FROM AUTHOR]