Electronics news and discussion thread

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First organic bipolar transistor developed
https://techxplore.com/news/2022-06-bip ... istor.html
by Dresden University of Technology

The invention of the transistor in 1947 by Shockley, Bardeen and Brattain at Bell Laboratories ushered in the age of microelectronics and revolutionized our lives. First, so-called bipolar transistors were invented, in which negative and positive charge carriers contribute to the current transport; unipolar field effect transistors were only added later. The increasing performance due to the scaling of silicon electronics in the nanometer range has immensely accelerated the processing of data. However, this very rigid technology is less suitable for new types of flexible electronic components, such as rollable TV displays or medical applications.

For such applications, transistors made of organic material, or carbon-based semiconductors, have come into focus in recent years. Organic field effect transistors were introduced as early as 1986, but their performance still lags far behind silicon components.

A research group led by Prof. Karl Leo and Dr. Hans Kleemann at the TU Dresden has now succeeded for the first time in demonstrating an organic, highly efficient bipolar transistor. Crucial to this was the use of highly ordered thin organic layers. This new technology is many times faster than previous organic transistors, and for the first time the components have reached operating frequencies in the gigahertz range (i.e., more than a billion switching operations per second).

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Research allows for 3D printing of 'organic electronics'
https://techxplore.com/news/2022-06-3d-electronics.html
by University of Houston

When looking at the future of production of micro-scale organic electronics, Mohammad Reza Abidian—associate professor of Biomedical Engineering at the University of Houston Cullen College of Engineering—sees their potential for use in flexible electronics and bioelectronics, via multiphoton 3D printers.

The newest paper from his research group examines the possibility of that technology. "Multiphoton Lithography of Organic Semiconductor Devices for 3D Printing of Flexible Electronic Circuits, Biosensors, and Bioelectronics" was published online in Advanced Materials.

Over the past few years, 3D printing of electronics have become a promising technology due to their potential applications in emerging fields such as nanoelectronics and nanophotonics. Among 3D microfabrication technologies, multiphoton lithography (MPL) is considered the state-of-the-art amongst the microfabrication methods with true 3D fabrication capability, excellent level of spatial and temporal control, and the versatility of photosensitive materials mostly composed of acrylate-based polymers/monomers or epoxy-based photoresists.

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Electrospinning promises major improvements in wearable technology

by American Institute of Physics
https://techxplore.com/news/2022-06-ele ... ology.html

Wearable technology has exploded in recent years. Spurred by advances in flexible sensors, transistors, energy storage, and harvesting devices, wearables encompass miniaturized electronic devices worn directly on the human skin for sensing a range of biophysical and biochemical signals or, as with smart watches, for providing convenient human-machine interfaces.

Engineering wearables for optimal skin conformity, breathability, and biocompatibility without compromising the tunability of their mechanical, electrical, and chemical properties is no small task. The emergence of electrospinning—the fabrication of nanofibers with tunable properties from a polymer base—is an exciting development in the field.

In APL Bioengineering, researchers from Tufts University examined some of the latest advances in wearable electronic devices and systems being developed using electrospinning.

"We show how the scientific community has realized many remarkable things using electrospun nanomaterials," said author Sameer Sonkusale. "They have applied them for physical activity monitoring, motion tracking, measuring biopotentials, chemical and biological sensing, and even batteries, transistors, and antennas, among others."

Sonkusale and his colleagues showcase the many advantages electrospun materials have over conventional bulk materials.

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New type of semiconductor may advance low-energy electronics
https://techxplore.com/news/2022-07-sem ... onics.html
by Jamie Oberdick, Pennsylvania State University

A research partnership between Penn State and the Massachusetts Institute of Technology (MIT) could enable an improved method to make a new type of semiconductor that is a few atoms thin and interacts with light in an unusual way. This new semiconductor could lead to new computing and communications technologies that use lower amounts of energy than current electronics.

The new type of semiconductor, tin selenide (SnSe), would be useful for developing a new type of electronics known as "photonics" that use particles of light, or photons, to store, manipulate and transmit information. Traditional electronics use electrons to do this, while photonics use photons. Tin selenide is a binary compound consisting of tin and selenium in a 1:1 ratio.

The material has a peculiar interaction with light that gives it great potential for use in electronics.

"It can be described as a material that has two different colors, meaning that depending on the orientation that you look at it, you will observe a different color," said Wouter Mortelmans, a postdoctoral associate in the Department of Materials Science and Engineering at MIT, and lead author of the study. "This peculiar optical property could be very useful to compute, store, or transmit information using light."

To make use of these orientation-dependent properties, it is very important that the fabrication of the material is done with atomic-precision control, said Mortelmans. The dependence of color on material orientation would enable faster and easier inspection of material quality.

"We need a reliable way to make the material, to manufacture devices to spec, without worrying about random, natural variations," said Rafael Jaramillo, Thomas Lord Associate Professor of Materials Science and Engineering at MIT and senior author of the study published in ACS Nano.

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Have researchers found the best semiconductor of them all?

by David L. Chandler, Massachusetts Institute of Technology
https://techxplore.com/news/2022-07-semiconductor.html

Silicon is one of the most abundant elements on Earth, and in its pure form the material has become the foundation of much of modern technology, from solar cells to computer chips. But silicon's properties as a semiconductor are far from ideal.

For one thing, although silicon lets electrons whizz through its structure easily, it is much less accommodating to "holes"—electrons' positively charged counterparts—and harnessing both is important for some kinds of chips. What's more, silicon is not very good at conducting heat, which is why overheating issues and expensive cooling systems are common in computers.

Now, a team of researchers at MIT, the University of Houston, and other institutions has carried out experiments showing that a material known as cubic boron arsenide overcomes both of these limitations. It provides high mobility to both electrons and holes, and has excellent thermal conductivity. It is, the researchers say, the best semiconductor material ever found, and maybe the best possible one.

So far, cubic boron arsenide has only been made and tested in small, lab-scale batches that are not uniform. The researchers had to use special methods originally developed by former MIT postdoc Bai Song to test small regions within the material. More work will be needed to determine whether cubic boron arsenide can be made in a practical, economical form, much less replace the ubiquitous silicon. But even in the near future, the material could find some uses where its unique properties would make a significant difference, the researchers say.

The findings are reported in the journal Science, in a paper by MIT postdoc Jungwoo Shin and MIT professor of mechanical engineering Gang Chen; Zhifeng Ren at the University of Houston; and 14 others at MIT, the University of Houston, the University of Texas at Austin, and Boston College.

Earlier research, including work by David Broido, who is a co-author of the new paper, had theoretically predicted that the material would have high thermal conductivity; subsequent work proved that prediction experimentally. This latest work completes the analysis by confirming experimentally a prediction made by Chen's group back in 2018: that cubic boron arsenide would also have very high mobility for both electrons and holes, "which makes this material really unique," says Chen.

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An ultrafast and highly performing nonlinear splitter based on lithium niobate
https://techxplore.com/news/2022-08-ult ... based.html
by Ingrid Fadelli , Tech Xplore

Optics, technologies that leverage the behavior and properties of light, are the basis of many existing technological tools, most notably fiber communication systems that enable long- and short-distance high-speed communication between devices. Optical signals have a high information capacity and can be transmitted across longer distances.

Researchers at California Institute of Technology have recently developed a new device that could help to overcome some of the limitations of existing optical systems. This device, introduced in a paper published in Nature Photonics, is a lithium niobate-based device that can switch ultrashort light pulses at an extremely low optical pulse energy of tens of femtojoules.

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Print, recycle, repeat: Scientists demonstrate a biodegradable printed circuit
https://techxplore.com/news/2022-08-rec ... rcuit.html
by Theresa Duque, Lawrence Berkeley National Laboratory

According to the United Nations, less than a quarter of all U.S. electronic waste gets recycled. In 2021 alone, global e-waste surged at 57.5 million tons, and only 17.4% of that was recycled.

Some experts predict that our e-waste problem will only get worse over time, because most electronics on the market today are designed for portability, not recyclability. Tablets and readers, for example, are assembled by gluing circuits, chips, and hard drives to thin layers of plastic, which must be melted to extract precious metals like copper and gold. Burning plastic releases toxic gases into the atmosphere, and electronics wasting away in landfill often contain harmful materials like mercury, lead, and beryllium.

But now, a team of researchers from the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) and UC Berkeley have developed a potential solution: a fully recyclable and biodegradable printed circuit. The researchers, who reported the new device in the journal Advanced Materials, say that the advance could divert wearable devices and other flexible electronics from landfill, and mitigate the health and environmental hazards posed by heavy metal waste.

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imple technique ushers in long-sought class of semiconductors

by Osaka University
https://phys.org/news/2022-08-simple-te ... class.html

Breakthroughs in modern microelectronics depend on understanding and manipulating the movement of electrons in metal. Reducing the thickness of metal sheets to the order of nanometers can enable exquisite control over how the metal's electrons move. By doing so, one can impart properties that aren't seen in bulk metals, such as ultrafast conduction of electricity. Now, researchers from Osaka University and collaborating partners have synthesized a novel class of nanostructured superlattices. This study enables an unusually high degree of control over the movement of electrons within metal semiconductors, which promises to enhance the functionality of everyday technologies.

Precisely tuning the architecture of metal nanosheets, and thus facilitating advanced microelectronic functionalities, remains an ongoing line of work worldwide. In fact, several Nobel prizes have been awarded on this topic. Researchers conventionally synthesize nanostructured superlattices—regularly alternating layers of metals, sandwiched together—from materials of the same dimension; for example, sandwiched 2D sheets. A key aspect of the present researchers' work is its facile fabrication of hetero-dimensional superlattices; for example, 1D nanoparticle chains sandwiched within 2D nanosheets

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Novel carrier doping in p-type semiconductors enhances photovoltaic device performance by increasing hole concentration
https://phys.org/news/2022-09-carrier-d ... ltaic.html
by Tokyo Institute of Technology

Perovskite solar cells have been the subject of much research as the next generation of photovoltaic devices. However, many challenges remain to be overcome for the practical application. One of them concerns the hole transport layer (p-type semiconductor) in photovoltaic cells that carries holes generated by light to the electrode.

In conventional p-type organic transport semiconductors, hole dopants are chemically reactive and degrade the photovoltaic device. Inorganic p-type semiconductors, which are chemically stable, are promising alternatives, but fabrication of conventional inorganic p-type semiconductors requires high temperature treatment. In this regard, the p-type inorganic semiconductors that can be fabricated at low temperatures and have excellent hole transport ability have been desired.

Inorganic p-type copper iodide (CuI) semiconductor is a leading candidate for such hole transport materials in photovoltaic device applications. In this material, native defects give rise to charge imbalance and free charge carriers. However, the overall number of defects is generally too low for satisfactory device performance.

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A navigation system with 10 centimeter accuracy
https://techxplore.com/news/2022-11-cen ... uracy.html
by Delft University of Technology

Researchers of Delft University of Technology, Vrije Universiteit Amsterdam and VSL have developed an alternative positioning system that is more robust and accurate than GPS, especially in urban settings. The working prototype that demonstrated this new mobile network infrastructure achieved an accuracy of 10 centimeters.

This new technology is important for the implementation of a range of location-based applications, including automated vehicles, quantum communication and next-generation mobile communication systems. The results were published today (Nov. 16) in Nature.

Much of our vital infrastructure relies on global navigation satellite systems such as the U.S. GPS and EU Galileo. Yet these systems that rely on satellites have their limitations and vulnerabilities. Their radio signals are weak when received on Earth, and accurate positioning is no longer possible if the radio signals are reflected or blocked by buildings.

"This can make GPS unreliable in urban settings, for instance," says Christiaan Tiberius of Delft University of Technology and coordinator of the project, "which is a problem if we ever want to use automated vehicles. Also, citizens and our authorities actually depend on GPS for many location-based applications and navigation devices. Furthermore, so far we had no back-up system."

The aim of the project entitled SuperGPS was to develop an alternative positioning system that makes use of the mobile telecommunication network instead of satellites and that could be more robust and accurate than GPS.

"We realized that with a few cutting-edge innovations, the telecommunication network could be transformed into a very accurate alternative positioning system that is independent of GPS," says Jeroen Koelemeij of Vrije Universiteit Amsterdam. "We have succeeded and have successfully developed a system that can provide connectivity just like existing mobile and Wi-Fi networks do, as well as accurate positioning and time distribution like GPS."

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SCIENTISTS BUILD CIRCUIT BOARDS BASED ON MUSHROOMS

MycelioTronics

Electronic waste, also known as "e-waste," is a major polluter, not to mention an increasingly difficult issue to combat. Excitingly, however, a team of Austrian scientists are working on a creative new solution to solve at least part of the e-waste puzzle: they're making biodegradable substrates for electronics out of mushroom skins.

Yes, really. And per the scientists' proof-of-concept paper published in Science Advances, these materials — dubbed "MycelioTronics — are showing some incredible promise as a possible replacement for traditionally plastic printed circuit boards, among other applications.

https://futurism.com/the-byte/circuit-board-mushrooms

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Building a 900-pixel imaging sensor using an atomically thin material
https://techxplore.com/news/2022-11-pix ... -thin.html
by Bob Yirka , Tech Xplore

A team of researchers at Penn State University has developed a 900-pixel imaging sensor using an atomically thin material. In their paper published in the journal Nature Materials, the group describes how they built their new sensor and possible uses for it.

Sensors that react to light have become very common in the modern world—lights that turn on when the presence of an intruder is detected, for example. Such sensors are typically made of a grid of pixels, each of which are reactive to light. Performance of such sensors are based on measurements of responsivity, and which parts of light they detect.

Most are designed with certain noise-to-signal constraints. In this new effort, the researchers noted that most such sensors are also very inefficient, using far more electricity than should be the case for such devices.

To make a sensor that would be more efficient, the researchers looked at the materials that are used to make those now in use—generally a silicon complementary metal oxide semiconductor serves as the backbone. And it was the backbone where the researchers focused their effort. To make a sensor that would be more efficient, they replaced the traditional backbone with one made from molybdenum disulfide, a material that, like graphene, can be grown as a one atom thick sheet.

In their work, they grew it on a sapphire base via vapor deposition. Then then lifted the finished product from the base and laid it on a base of silicon dioxide that had already been wire etched. They then finished their product by etching additional wiring on the top.

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Using lasers to bond semiconductor electronics components
https://phys.org/news/2022-12-lasers-bo ... nents.html
by Pol Sopeña and David Grojo

Today, lasers are well-established in daily life, even if it is sometimes hard to tell what and where they are. As an example, we can find them in CD/DVD readers or medical applications like cancer and eye surgery, being essential tools in a vast range of multidisciplinary fields. All of this is the result of constant progress and development, from the first Maiman's ruby laser (1960) to the attosecond lasers, passing through exotic, funny demonstrations like Jell-O lasers.

In the quest to constantly obtain more intense sources, ultrashort lasers (with pulses in the femtosecond regime) represented a clear breakthrough, as they allowed high-intensity delivery in confined spaces on the nanoscale. In particular, they allow inducing nonlinear absorption phenomena which, for instance, permits locally modifying the interior of transparent materials with a low thermal budget, not achievable with other laser sources. Some demonstrations include waveguides writing in glasses or creating 3D complex patterns with polymers.

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Photonic chip with record-breaking radio frequency dynamic range
https://phys.org/news/2022-12-photonic- ... uency.html
by University of Twente

Researchers at the University of Twente have developed a revolutionary programmable integrated microwave photonic filter with a record-breaking dynamic range. This represents a major breakthrough in the integration of functionality and performance in radio frequency photonic signal processors.

The paper is published in the journal Nature Communications.

Prof. Dr. David Marpaung, one of the authors of the study says, "Our work breaks the conventional and fragmented approach of integration, functionality and performance that currently prevents the adoption of these photonic systems in real applications. Traditional radio frequency filters can only work in a narrow frequency range, meaning you need several separate filters for broadband operation. Our device is integrated, broadband, and has an enormous dynamic range, making it possible to use just a single photonic circuit for various frequency ranges."

Many applications

The research shows that the filter can play a key role in modern radio frequency and microwave applications, including cognitive radio, multi-band all-spectrum communications, and broadband programmable front-ends. Before this discovery, programmable microwave photonic circuits with such advanced functions had poor performance. "Versatile programming of the chip can easily give in to various disturbances like loss, noise, and distortion of the signal," explains Marpaung.

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A Bayesian machine based on memristors
https://techxplore.com/news/2023-01-bay ... stors.html
by Ingrid Fadelli , Tech Xplore

Over the past few decades, the performance of machine learning models on various real-world tasks has improved significantly. Training and implementing most of these models, however, still requires vast amounts of energy and computational power.

Engineers worldwide have thus been trying to develop alternative hardware solutions that can run artificial intelligence models more efficiently, as this could promote their widespread use and increase their sustainability. Some of these solutions are based on memristors, memory devices that can store information without consuming energy.

Researchers at Université Paris-Saclay- CNRS, Université Grenoble-Alpes-CEA-LETI, HawAI.tech, Sorbonne Université, and Aix-Marseille Université-CNRS have recently created a so-called Bayesian machine (i.e., an AI approach that performs computations based on Bayes' theorem), using memristors. Their proposed system, introduced in a paper published in Nature Electronics, was found to be significantly more energy-efficient than currently employed hardware solutions.

"Artificial intelligence is making major progress today but faces a challenge: its considerable energy consumption," Damien Querlioz, one of the researchers who carried out the study, told TechXplore. "It is now well understood that this consumption comes from the separation, in computers, between computation and memory functions. As artificial intelligence uses a lot of data, it requires a lot of memory, which is costly to access in terms of energy. Our brains are much more energy efficient because the memory functions are integrated as close as possible to the computation functions, and we wanted to reproduce this strategy."

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A new elastic polymer dielectric to create wafer-scale stretchable electronics
https://techxplore.com/news/2023-02-ela ... hable.html
by Ingrid Fadelli , Tech Xplore

Over the past few years, material scientists and electronics engineers have been trying to fabricate new flexible inorganic materials to create stretchable and highly performing electronic devices. These devices can be based on different designs, such as rigid-island active cells with serpentine-shape/fractal interconnections, neutral mechanical planes or bunked structures.

Despite the significant advancements in the fabrication of stretchable materials, some challenges have proved difficult to overcome. For instance, materials with wavy or serpentine interconnect designs commonly have a limited area density and fabricating proposed stretchable materials is often both difficult and expensive. In addition, the stiffness of many existing stretchable materials does not match that of human skin tissue, making them uncomfortable on the skin and thus not ideal for creating wearable technologies.

Researchers at Sungkyunkwan University (SKKU), Institute for Basic Science (IBS), Seoul National University (SNU), and Korea Advanced Institute of Science and Technology (KAIST) have recently fabricated a vacuum-deposited elastic polymer for developing stretchable electronics. This material, introduced in Nature Electronics, could be used to create stretchy field-effect transistors (FETs), which are primary components of most electronic devices on the market today.

"Recently, various approaches for adopting soft materials have been proposed for developing intrinsically stretchable electronics which does not need any specific structural designs owing to their intrinsic deformability," Donghee Son, one of the researchers who carried out the study, told Tech Xplore. "However, such devices employed solution-processed dielectric materials and thereby encounter critical challenges in achieving high electrical performances."

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Fully recyclable printed electronics ditch toxic chemicals for water
https://phys.org/news/2023-04-fully-rec ... toxic.html
by Ken Kingery, Duke University

Engineers at Duke University have produced the world's first fully recyclable printed electronics that replace the use of chemicals with water in the fabrication process. By bypassing the need for hazardous chemicals, the demonstration points down a path industry could follow to reduce its environmental footprint and human health risks.

The research appeared online Feb. 28 in the journal Nano Letters.

One of the dominant challenges facing any electronics manufacturer is successfully securing several layers of components on top of each other, which is crucial to making complex devices. Getting these layers to stick together can be a frustrating process, particularly for printed electronics.

"If you're making a peanut butter and jelly sandwich, one layer on either slice of bread is easy," explained Aaron Franklin, the Addy Professor of Electrical and Computer Engineering at Duke, who led the study. "But if you put the jelly down first and then try to spread peanut butter on top of it, forget it, the jelly won't stay put and will intermix with the peanut butter. Putting layers on top of each other is not as easy as putting them down on their own—but that's what you have to do if you want to build electronic devices with printing."

In previous work, Franklin and his group demonstrated the first fully recyclable printed electronics. The devices used three carbon-based inks: semiconducting carbon nanotubes, conductive graphene and insulating nanocellulose. In trying to adapt the original process to only use water, the carbon nanotubes presented the largest challenge.

To make a water-based ink in which the carbon nanotubes don't clump together and spread evenly on a surface, a surfactant similar to detergent is added. The resulting ink, however, does not create a layer of carbon nanotubes dense enough for a high current of electrons to travel across.

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Researchers Discover New Circuit Element – The Meminductor
https://scitechdaily.com/researchers-di ... minductor/
By Rachel Rose, Texas A&M Engineering April 12, 2023
Logic Circuit Concept

The research team published their new circuit element discovery in the February issue of the journal Scientific Reports.
Physical evidence of meminductance proven

Dr. H. Rusty Harris, an Associate Professor in the Department of Electrical and Computer Engineering at Texas A&M University, has discovered a novel circuit element referred to as a meminductor.

A circuit element refers to an electrical component utilized to regulate and guide the flow of electricity within an electrical circuit. The traditional three circuit elements are the resistor, capacitor, and inductor. Recently, within the past 15 years, two additional circuit elements, the memristor, and the memcapacitor, have been discovered. These newer circuit components are referred to as the “mem-” versions of their classical counterparts and exhibit unique current and voltage properties that depend on previous values of current or voltage in time, acting like a memory.

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Researchers design flexible electronics for stretchable OLED display
https://techxplore.com/news/2023-04-fle ... splay.html
by Sarah C.P. Williams, University of Chicago

Imagine a thin, digital display so flexible that you can wrap it around your wrist, fold it in any direction, or curve it over your car's steering wheel. Researchers at the Pritzker School of Molecular Engineering (PME) at the University of Chicago have designed just such a material, which can bend in half or stretch to more than twice its original length while still emitting a fluorescent pattern.

The material, described in Nature Materials, has a wide range of applications, from wearable electronics and health sensors to foldable computer screens.

"One of the most important components of nearly every consumer electronic we use today is a display, and we've combined knowledge from many different fields to create an entirely new display technology," said Sihong Wang, assistant professor of molecular engineering, who led the research with Juan de Pablo, Liew Family Professor of Molecular Engineering.

"This is the class of material you need to finally be able to develop truly flexible screens," added de Pablo. "This work is really foundational and I expect it to allow many technologies that we haven't even thought of yet."

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No More Toxic Chemicals – The World’s First Fully Recyclable Printed Electronics

https://scitechdaily.com/no-more-toxic- ... ectronics/
By Duke University April 13, 2023

The first-of-a-kind demonstration indicates that a greener future for the electronics sector is possible.

Duke University engineers have created the world’s first printed electronics that can be fully recycled. Their innovative solution replaces the use of harmful chemicals with water during the fabrication process, thereby reducing the environmental impact and potential health risks associated with the use of hazardous chemicals. This demonstration opens up a new avenue for the industry to follow in reducing its ecological and health footprint.

The research was recently published in the journal Nano Letters.

One of the major obstacles that electronics manufacturers face is successfully securing several layers of components on top of each other, which is crucial for the production of sophisticated devices. This can be a challenging task, especially for printed electronics, where ensuring proper adhesion of layers is often a source of frustration.