The discovery of two-dimensional materials has revolutionized condensed matter physics, with transition metal dichalcogenides (TMDCs) offering tunable electronic and optical properties. Monolayer tungsten diselenide WSe $_2$ , a direct bandgap semiconductor with strong excitonic effects, is especially promising for optoelectronics. When two WSe $_2$ monolayers are stacked with controlled twisting angles, the resulting twisted bilayer (tB) material forms a moiré superlattice that significantly modifies its electronic structure and optical response through interlayer coupling and band reconstruction. In a systematic study employing photoluminescence (PL) and differential micro-reflectance contrast ( $\mu$ RC) spectroscopy and supported by first-principles calculations, we investigate the optical properties of tB WSe $_2$ for twisting angles $ 0^\circ \lt \theta \lt 60^\circ $ . Excitonic peaks (A, B, C, D) exhibit angle-dependent energy shifts. Notably, A and C excitons show characteristic energy splittings that reflect twisting-angle-modulated interlayer hybridization and spin–orbit coupling effects. The A exciton shows local minima at $0^\circ$ and $60^\circ$ , and a maximum near $30^\circ$ . This pattern reflects variations in interlayer hybridization—stronger coupling at $0^\circ$ and $ 60^\circ$ , weaker at intermediate angles—consistent with moiré-induced modifications. Our work reveals the periodic modulation of exciton energies in WSe $_2$ homo-bilayers across a wide range of twisting angles, directly linking these variations to interlayer coupling strength and spin–orbit splitting. Our findings provide clear experimental–theoretical consistency, identifying the twisting angle as an effective tuning knob for excitonic transitions and interlayer interactions in TMDC bilayers. The work contributes to the understanding of the structure–property relationships in twisted TMDC materials, and the results may lead to new design principles for next-generation, moiré-engineered optoelectronic and quantum devices.

This paper discusses the use of inkjet printing technology for the direct deposition of catalyst layers onto 8 mu m or 15 mu m thick polymer electrolyte membranes (PEM) with the view to industrial production. Here, the challenges in applying larger material quantities within a few seconds and the impact on the homogeneity of the catalyst layers and the platinum distribution is presented. Different approaches for the deposition and drying of the catalyst material as well as detailed investigations of the printed layers are conducted. As result, a sequential deposition of defined smaller material quantities to a 12 cm2 area is an expedient approach to control and restrict the flow of wet material and achieve homogeneous catalyst layers directly on these thin membranes with least swelling and minor crack formation. As a quality control, micro X-ray fluorescence (XRF) measurements were carried out and reveal a drastically reduced material agglomeration and therefore, a uniform platinum distribution for the mentioned printing approach. Furthermore, the electrochemical analysis in terms of electrochemical impedance spectroscopy (EIS), the resulting O2 diffusion resistances as well as protonic resistance and the U-I-characteristics reveal a clear trend of the performance depending on the platinum loading, number of printed layers and porosity. By implementing the most favorable printing approach, a current density of 1.58 A/ cm2 at 0.6 V cell voltage with a peak power density of 1.21 W/cm2 could be achieved.

Hydrogen mobility represents a progressive, low carbon imprint option for the replacement of internal combustion engines. A core of this technology is low-temperature fuel cell with proton-exchange membrane (LTPEMFC), using hydrogen and atmospheric oxygen as fuel and oxidant, respectively. The membrane-electrode assembly (MEA) which makes up a cell consists of polymer electrolyte membrane, cathodic and anodic catalyst layers and carbon-based porous gas-diffusion layers. LTPEMFC require Pt catalyst on both the anode and the cathode in non-negligible total amount, increasing investing costs for stack unit. In order to maximise fuel cell performance, the formation of three-phase boundary has to be achieved during deposition of catalyst layers, interconnecting Pt nanoparticles on carbon support and ionomer with membrane in complex, porous structure. The quality of catalyst layer determines to high degree final MEA performance. Catalyst layers can be deposited either on gas-diffusion layers or onto the membrane, with latter being considered a more advantageous and feasible approach. Deposition itself can be realised by various methods, including airbrush spraying, decal printing, doctor blade deposition from paste and, most often used nowadays, ultrasonically-assisted spray coating. Each of these methods brings its own advantages and disadvantages, though the common problem of these methods is low suitability for serial production. On the other hand, the quality of so-prepared catalyst layers is sufficient. Methods for large-capacity coating of catalyst layers, especially roll-to-roll technology have exactly opposite pros and cons, high output but unsatisfactory layer quality. An interesting alternative to state-of-the-art catalyst layer fabrication procedures is inkjet printing. Inkjet printing is a well-established technology, though the application in LTPEMFC field brings various issues, mainly connected to quality of layers and prevention of nozzle-clogging during the deposition. Solving of these issues, however, will result in technology suitable for catalyst layer printing, combining high production throughput, very good reproducibility, minimal losses of the ink, suitability to additive manufacturing and possibility of printing specific geometries with gradient layer thickness. Accordingly, the goal of this study is the comparison of catalyst layers, deposited onto the membrane by ultrasonically-assisted spray coating and inkjet printing, in terms of morphology, electric conductivity, permeability and performance in LTPEMFC, using commercially-available materials for layer fabrication. Catalyst layers of the same composition and Pt loading were deposited by either ultrasonically-assisted spray coating or inkjet printing onto FTO conductive glass for the determination of electric conductivity, onto gas-diffusion layer for permeability determination in Loschmidt cell and FIB-SEM morphology studies and onto the membrane for the fabrication of MEA and evaluation of its performance in LTPEMFC. Characterisation of layers deposited on materials above underlined feasibility of inkjet printing for catalyst layer fabrication. In comparison with sprayed layers, layers prepared by inkjet printing tend to be thinner, more homogenous and compact. This results in superior electric conductivity but lower permeability at the same time. Single cell tests proved that performance of inkjet-printed layers is at least on par with sprayed ones, surpassing them with optimised ink composition and Pt loading. Overall, inkjet printing technology is a highly attractive technology for industrial catalyst layer production with great possibilities for contributing to decrease LTPEMFC unit’s investment costs. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 958174. This project is co-financed from the state budget by the Technology agency of the Czech Republic under the M-ERA.Net Programme, project No. TH80020006. This work was supported by the project "The Energy Conversion and Storage", funded as project No. CZ.02.01.01/00/22_008/0004617 by Programme Johannes Amos Commenius, call Excellent Research. This project is co-financed with tax funds on the basis of the budget passed by the Saxon state parliament.

In battery systems, there are several established form factors targeting mass market applications, like D, C, AA, AAA series, lithium round cells, and coin cells. Besides these standardized batteries, in printed electronics, there are several approaches to realize flat batteries of different material systems fabricating primary and secondary battery types. For a dedicated application in agriculture, a sensor system requires a degradable primary battery. In this paper, the development of a dedicated zinc–carbon battery is described, supplying the sensor application with 4.5 Vnom. The battery has a 170 mm length and a 23 mm outer diameter. while the inner core is open for the antenna system of the application. The active area is up to 161 cm2. The design and manufacturing aspects are described. The rolled-up battery system is fully charged after manufacturing and ready to operate. It may remain inside the degradable sensor system after use in the field.

Robot-guided inkjet printing technology offers a new way for the digital and additive deposition of low-viscous inks to be made directly onto arbitrary surfaces and, thus, enables the production of individualized printed electronics on large-scale objects. When compared to conventional flatbed printing, the distance between the nozzle plate and the object's surface varies and needs to be considered in order to match the accuracy requirements needed for the positioning of single drops. Knowledge about applicable distance limits and the influence of tunable print parameters is crucial for improving the print process and results. This study discusses the sources of errors in the inkjet printing process onto 3D objects and presents extensive results about position accuracy in relation to jetting distance for different parameter sets of functional inks, drop volumes, and piezo voltages. Additionally, an efficient novel method was applied to determine the drop position accuracy of inkjet droplets in relation to the jetting distance. The method relies on cylinder geometry for the object and an inkjet head that is guided by a six-axis robot manipulator along the cylinder's axis. For the determination of drop placement accuracy, the position of single dots on the surface was compared to a model which considered the cylinder radii, drop velocity, and the movement speed of the guided inkjet printhead. The method and the extensive research results can be utilized for the prediction of achievable drop placement accuracy and the prior definition of distance limits.

The constantly growing global population is to be sustainably supplied with food. Due to climatic changes and increasing problems in protecting the environment, farmers are faced with great challenges. In order to automate, specify and simplify processes, reliable decision-making bases for the control of irrigation, fertilization and plant protection measures with a close-meshed database are required. This can be achieved with cost-efficiently produced and environmentally friendly sensor systems for monitoring cultivated areas. Such a monitoring system is currently being developed, first laboratory samples are available and are being tested step by step in laboratory and field. The single sensor devices consist of a miniaturized electronic module with single-chip radio system, sensors for measuring temperature, soil tension, in the near future leaf wetness and nitrate. The sensors and the electronic module are fabricated from materials that are biodegradable or inert with a minimum amount of metal and ceramic and allow for remaining them on the field when harvesting. The device is powered by a biodegradable zinc-manganese dioxide battery. For wireless communication, a printed antenna on a wood carrier is used. A gateway collects the data transmitted by the distributed sensor devices and brings it to the internet to a central server running an expert system. The technologies used for the assembly, such as roll-to-roll and screen printing, and the materials used, such as wood and paper, enable inexpensive and partly biodegradable sensors that are applied to the field once per growing season in high density. This enables fine-mesh, site-specific treatments and a further reduction in water, fertiliser and pesticide use.

We report large exciton energy tuning (∼62 meV) in WSe2monolayersviasubstrate induced non-degenerate electron doping.

In this paper, the suitability of integrating a digital manufacturing tool i.e. inkjet technology is exemplified to increase the electrical performance of thin-film based Copper Indium Gallium Selenide (CIGS) photovoltaic (PV) modules. Typically, the series connection within the PV module is established conventionally by three adjacent scribing lines at different deposition stages (patterning P1, P2 and P3). The total width of these three scribes is typically in the order of several 100's of microns and is electrically inactive, so these regions are lost areas for current generation (up to 5% “dead area”). To reduce the line width of the first scribe (P1) without compromising on the electrical parameters, we have concentrated on accurately filling of the interconnect P1-trenches with insulating material using inkjet technology, as initial step to realize the concept for dead area reduction by developing a P1-filling process (< 80 μm printed filling width) for laser structured/patterned trenches of ~50 μm width. With the right combination of carefully selected material interface, inkjet printhead, deposition settings, pattern digitalization & other parameters, we are able to develop an industry relevant micro-filling process. And, show an increase in the performance of PV cells, as compared to the reference modules. The results lay the foundation for direct up-scaling to industrial-size substrate areas and open up the possibility to realize all kinds of advanced interconnect schemes for the next generation thin-film CIGS PV modules.

Inkjet printing is a versatile, contactless and accurate material deposition technology. The present work is focused on developing innovative strategies for inkjet printing of CatalystCoated Membranes (CCM) by performing Additive Manufacturing (AM) applied to Polymer Electrolyte Membrane Fuel Cells (PEMFC), without resorting to intermediate substrates. Three different approaches for AM are presented and discussed: a) inkjet-printing of the membrane ionomer layer , the top catalyst layer; b) inkjet-printing of both catalyst layers onto a membrane; c) inkjet-printing of the ionomer layer as well as the catalyst layers onto the reinforcement layer of the membrane. The produced catalyst and membrane layers were characterized and proved uniform in terms of catalyst loading (0.2-0.4 and 0.08 mgPt cm(-2) for cathode and anode, respectively), ionomer distribution and thick-ness homogeneity (4 mu m for catalyst layers). The fully inkjet-printed CCM outperformed conventionally made assemblies in electrochemical-performance testing, even reaching 15% higher power density. (C) 2022 The Authors. Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.

Herein, we report the environmental impact quantification of a newly developed fully printed electrochemical device to assist a colorimetric detection of phosphate in saliva. The evaluation of the analytical procedure was performed according to the principles of Green Analytical Chemistry and White Analytical Chemistry. The standard method for phosphate detection relies on a reaction between phosphate and molybdate in presence of antimony potassium tartrate and ascorbic acid, using strong acid conditions and high volumes of reagents (100–500 mL). To deliver an eco-friendly method, we have combined a screen-printed electrode with a liquid electrolyte battery and inkjet-printed conductive paths to develop a fully printed device on a flexible polymer substrate avoiding the use of ascorbic acid and using a small amount of reagents. The printed sensor was first developed and optimized for phosphate detection in saliva, allowing for a detection limit equal to 26 µM and satisfactory repeatability (relative standard deviation value of 7.5%). Finally, the AGREE and the RGB assessment tools were applied for a quantitative evaluation of the proposed sensor and reference method, in agreement with the Green Analytical and White Analytical principles. The results demonstrated the lower environmental impact of the proposed sensor, as well as the suitability of this novel approach for phosphate detection in saliva.

Spherical colloidal photonic supraparticle systems or assemblies (SCAs) are investigated as a model system for confined optical and photonic components. Simulations of the reflection spectrum to calculate their photonic and optical properties for different parameter constellations are compared with experimental studies by microreflectance spectroscopy (mu RS) on SCAs fabricated by inkjet in-flight deposition, proving the existence of a dual-band reflection spectrum originating from the supraparticle system. Finite-difference time-domain (FDTD) calculations are employed to verify these findings as a function of structural parameters. Both, theory and experiment, show a double reflection peak for the SCAs and agree well in the variation of position and shape, scaling clearly with the packing density of the SCAs. Reducing this parameter from 0.6 to 0.3, the higher-wavelength reflection maximum decreases in intensity and increases in width but keeps its spectral position. The lower-wavelength reflection maximum decreases in intensity, increases in width and shows a red shift. The results clearly indicate that aspects of disorder decisively contribute to the particular spectral photonic properties of the supraparticle system which are usually related to order in photonic crystals. This finding can stipulate novel, tailor-made nanostructured optical components such as low-dimensional micro resonators and waveguides.

Herein, the inkjet printing of bioresorbable materials tuned to function as electrode, dielectric, and semiconductor layers is reported, thereby developing multilayered microelectronic devices such as capacitors and thin‐film transistors, potentially applicable to address specific medical needs. Polymers and natural materials, e.g., poly(3,4‐ethylenedioxythiophene)‐poly(styrenesulfonate), shellac, and β‐carotene, indigo inks are implemented using jettable formulations, that are either commercially procured or self‐formulated, designed explicitly to deposit fundamental layers for capacitors and transistors. Several parameters are evaluated and adjusted to precisely define a layer's thickness, topology, and geometry, matching with the properties of a fully biodegradable Ormocere substrate, explicitly developed for the specific biological applications. Furthermore, these parameters support in acquiring the intended electrical properties of layers, i.e., conductivity, insulation, semiconductivity, capacitance, and current versus voltage characteristics. The entire manufacturing process of devices is accomplished on the Ormocere substrate under ambient conditions and below 60 °C. The results exhibit that the electrical characteristics of the printed functional layers and devices show direct influence to the physical geometry of the printed features. A fully printed capacitor demonstrates capacitance of 1 nF cm−2, whereas transistors show p‐type and n‐type characteristics with current 0.18–5 μA and mobility 6 × 10−4–7 × 10−2 cm2 V−1 s−1.

The inkjet technology due to its gm-scale accuracy, up-scalability, efficient processing and industrial relevance, is widely accepted as a smart digital tool for manufacturing g-electronic devices on rigid and flexible substrates. Within this research, the inkjet technology is implemented to manufacture bio-compatible and bio-degradable conductive electrodes, contacts for electrical signal transmission/stimulation and development of the multilayered devices e.g. capacitors and thin-film-transistors (TFTs) along with suitable barrier layer characteristics, for implants in the medical applications. To accomplish such competitive goals, it is essential to select the most optimal functional materials, which would firstly fulfill the electrical needs of the device and secondly support processibility using the inkjet technology. The functional materials such as poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate), natural semiconductors and shellac are here utilized in form, of commercially available and self-formulated inks, that are addressed carefully to deposit fundamental layers for printing capacitors and TFTs. The focus of this work is to decide on solution-processable device architectures e.g. BGBC TFTs, followed by the development and optimization of the deposition parameters for the specific materials tuned to defined layer thicknesses and concentrations. This supports in acquiring the desired electrical characteristics of conductivity, capacitance, charge transportation etc, and thus the device performance. The results show that the manufactured devices are achieved successfully on the bio-degradable substrates, processed entirely under 60 °C and ambient conditions. The electrical characteristics of the devices show direct dependency to the physical dimensions of the printed features, by exhibiting certain performance merits i.e. 210 ± 50 pF/mm2 and 10 gA channel current..

Today various applications are designed to make life much easier for the consumer. For example you want to be accessible always and everywhere, and detect many parameters of your own body functions, not only in the medical field, but also in the leisure area. In times when fitness and healthiness is getting higher and higher, with dozens of apps which recognize if I slept well, drank enough, or my sport unit is effective, we have to think about an easy and undisturbing way to collect those data and send them for example to our smartphone or computer. With printed functional applications we are able to collect those data without disturbing the consumer, because they are light weighted and flexible. In the medical field as well, non-perceptible sensors and functional applications are as desirable as possible to affect patients. The more common the patient feels, despite monitored by sensors, the faster he will recover and, for example, be discharged from the hospital. This reduction in the period of illness allows an immense reduction in the incidence of the illness and examination costs.

Inkjet and screen printing technologies are well known in the graphic arts industry for the reproduction of texts, images, and graphics. During the last decades, these printing technologies have been attracting increasing interest for the deposition of functional materials, e.g., in the field of printed electronics and for biological applications. However, their usage is mainly limited to 2D applications, i.e., rather flat deposits ranging from nanometers to several tens of micrometers in thickness. For 3D applications, sophisticated additive manufacturing technologies are developed to manufacture structures with high shape complexities. Herein, the potential of standard inkjet and screen printing technology as tools for the development of functional 3D objects is demonstrated. 3D functional structures printed by inkjet and screen printing technology combining conductive and nonconductive materials to a multi‐material structure are shown. A metal nanoparticle ink formulation is applied to inkjet‐print conductive metal pillars with a high aspect ratio (in the range of 50) used as vertical interconnects. The interconnects are encapsulated with an inkjet‐printed polymeric ink formulation and finally used as conductive tracks to light up a solid‐state light‐emitting diode (LED). Screen printing is applied to print primary batteries used as the power source for the LED.

Various applications of functional devices need a tailored and reliable supply of electrical energy. Batteries are electrochemical systems that deliver energy for functional devices and applications. Due to the common use, several rigid types of batteries have been standardized. To fully integrate the battery into a product that is bendable, free in geometry and less than 1 mm thick, printing of power adaptable batteries is a challenging area of research. Therefore, the well-known zinc-manganese system, which is very promising due to its environmental sustainability and its simplicity, has been used to manufacture battery solutions on a new kind of substrate: technical textiles. Another challenge is the deposition of conductive patterns. At present, embroidery with metallic yarn is the only possibility to provide conducting paths on technical textiles, a time-consuming and elaborate process. Screen printed conductive pathways will generate a new momentum in the manufacturing of conductivity on textiles. (C) 2018 The Japan Society of Applied Physics

All printing and patterning technologies were developed long ago, when printing of batteries was not even thought of. Therefore, optimization processes targeted goals other than technical application of functional layers. Nevertheless, developments to date are a reasonable basis for adopting printing technologies for the deposition of material layers that can, for example, be employed in the manufacture of batteries. The printing process involves the application of a specific ink onto a chosen substrate to form a predefined patterned layer of a certain layer thickness. Numerous printing techniques have been established. Some, such as screen printing or coating technologies, are ideal for the deposition of homogenous functional layers of defined layer thickness in large areas. When dealing with small and sophisticated batteries, digital printing technologies such as dispensing or inkjet printing are appropriate technologies that may limit the particle sizes contained in the processed inks.

Since the end of the last century tremendous efforts have been spent to utilize various aspects of printed electronics' components. One aspect in driving electronics is to provide electrical energy for it. The most appropriate way is to employ printing approaches rather than assembly processes for the integration of battery technology. Doing so, the application basically can be fully printed – if all components are printable. Looking for commercial applications, there are already some available on the market: e.g. temperature logger, RFID smart tagging cards, or cosmetic patches. In this paper a review on printed primary batteries is presented and discussed. Since 2007 Fraunhofer ENAS and Chemnitz University of Technology are active in developing and manufacturing printed batteries and applications thereof. Besides the historical sketch also the current achievements are shown and discussed.

Organic and printed electronics integration has the potential to revolutionize many technologies, including biomedical diagnostics. This work demonstrates the successful integration of multiple printed electronic functionalities into a single device capable of the measurement of hydrogen peroxide and total cholesterol. The single-use device employed printed electrochemical sensors for hydrogen peroxide electroreduction integrated with printed electrochromic display and battery. The system was driven by a conventional electronic circuit designed to illustrate the complete integration of silicon integrated circuits via pick and place or using organic electronic circuits. The device was capable of measuring 8 μL samples of both hydrogen peroxide (0-5 mM, 2.72 × 10-6 A·mM-1) and total cholesterol in serum from 0 to 9 mM (1.34 × 10-8 A·mM-1, r2 = 0.99, RSD < 10%, n = 3), and the result was output on a semiquantitative linear bar display. The device could operate for 10 min via a printed battery, and display the result for many hours or days. A mobile phone "app" was also capable of reading the test result and transmitting this to a remote health care provider. Such a technology could allow improved management of conditions such as hypercholesterolemia.

Printed batteries are unique in their capability of providing customized electrical energy to various kinds of applications. A primary battery is fully charged during manufacture and so does not require charging prior to its first use. Therefore, the amount of energy included during production is immediately available for the designated application. Printing as a manufacturing technology enables the production of this type of battery with the ability to tailor voltage, energy content, and layout. One appropriate application for this type of energy supply is in single-use sensor devices used for blood testing. Such systems possess finite and well-defined energy requirements.In this paper, the development of a power supply based on printed battery technology for just such a sensor system is described. The application of the sensor system is for the measurement of cholesterol in human blood. During the research and development process, the requirement was to support electrical power to two different types of systems: one controlled by a Si-chip and the other controlled by an organic circuit. The first setup required an operating voltage of 3 to 4.5V while the second setup demanded +/-15 V. In this paper, the investigations and results for both types of batteries are described. Both types have been successfully characterized to fulfill the application demands.