Many alternatives to silicon are being developed, as it is believed that silicon transistors will reach their technological limits. 2-Dimensional materials are a class of nanomaterials defined by their property of being merely one or two atoms thick. Electrons in these materials are free to move in the two-dimensional plane, but their restricted motion in the third direction is governed by quantum mechanics.
2-D materials possess remarkable properties in their ability to be exceptionally strong, lightweight, flexible, and excellent conductors of heat and electricity. Two-dimensional (2-D) nanomaterials have shown promise for a new generation of nanoelectronic devices with potential to revolutionize many electronics applications such as solar cells, transistors, camera sensors, digital screens, and semiconductors.
Using 2D materials to make more efficient devices will have advantages of reduced carbon emissions, says Mr Wurdack a PhD student in the Nonlinear Physics Centre (NLPC) of the Research School of Physics . Two-dimensional materials have extraordinary properties such as extremely low resistance or highly efficient interactions with light. Because of these properties they could have big role in the fight against climate change. Eight percent of global electricity consumption in 2020, was due to information technologies, including computers, smartphones and large data centres of tech giants such as Google and Amazon. That figure is projected to double every decade as demand for AI services and smart devices skyrockets.
Graphene the most common 2-D nanomaterial for example is one million times thinner than paper, nearly transparent, and believed to be the strongest material in the world. Graphene, a single layer of carbon atoms and packed in a hexagonal lattice, has been found to be potentially useful as a light, low-power electronic component due to its many properties like strength, thermal and electrical conductivity.
Graphene was the first 2D material to enter the market, and there are now over 350 companies producing related products. We now find it in composites with enhanced mechanical or thermal properties, batteries, inks for printable electronics, photodetectors and some chemical and biological sensors. The next wave of products, such as solar cells, flexible devices, supercapacitors, water filters/desalinators and neural interfaces, is expected to emerge in the following years, as envisioned by the Graphene Flagship.
Fast-paced progress in understanding this 2D form of carbon atoms in a hexagonal lattice also opened up the exploration of 2D materials based on other elements or compounds and exhibiting various lattice configurations, which cover a wide spectrum of electrical and magnetic properties. Hence, 2D materials have repeatedly been predicted to be able to revolutionize electronics and other industrial sectors.
2D materials have been one of the most popular research fields of advanced materials over the past decade and the well-known 2D materials are graphene, MoS2 , hBN, WS2 , WSe2 . The most widely known and the precursor of the 2D materials are graphene, molybdenum disulfide (MoS2 ), and hexagonal boron nitride (hBN) with one atom thickness (named single layer) or more than two layers (referred to as multi-layer). The two-dimensional hexagonal lattice boron nitride (2D-hBN) has a similar structure as graphene and is named as white graphene which is an electrically insulating, chemically, and thermally stable ceramic material. They can also be combined to create new materials with enhanced thermal, electronic, mechanical, or optoelectronic properties that are named heterostructures.
MXenes are other kinds of 2D materials with higher saturable absorption (SA) than the other 2D materials. Having higher SA (up to 50%) provides increased modulation depth for optical isolator applications. 2D transition metal carbides, nitrides or carbonitrides have been introduced as MXene with a chemical formula of 1 M YnTx n + , where M is the transition metal (such as Sc, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, Mn ), Y is the carbon or nitrogen, T is the functional groups such as =O or -OH (n=1-3). They are produced by extracting the Y element from three-dimensional (3D) MYT phases with acidic chemical reactions.
Each of them has different properties that can be used in the different application fields; for example, graphene is found to be an excellent electrical conductor whereas hBN is an insulator with a large bandgap. However, contrary to electric conduction, hBN has better tribological properties than graphene, especially in high temperatures. MoS2 with different electrical, chemical, biological, and mechanical properties than other 2D materials are used in electronics, catalysis, biomedical, and energyrelated fields as nanosheets. Semiconductor MoS2 can retrieve the weakness of the graphene band gap and is used in optoelectronic applications.
However Graphene lacks a bandgap, the key property required to create transistors, logic and memory circuits. In recent years, new materials such as molybdenum disulfide, has been researched as a substitute for graphene and silicon. The monolayer molybdenum disulfide (MoS2), one of the promising 2D materials with a direct bandgap has high potential for applications in nano electronic devices, energy storage, photocatalysts, and chemical sensors. Molybdenum disulfide is a new 2-D material , consisting of a single-atomic layer of molybdenum sandwiched between two adjacent atomic layers of sulfide. This compound exists abundantly in nature as the mineral molybdenite, a crystal material found in rocks around the world, frequently taking the characteristic form of silver-colored hexagonal plates. The material has been used for many years as an industrial lubricant for aircraft and motorcycle engines.
Purdue Researchers 2D nanomaterial based on Tellurium with applications in high speed electronics to military surveillance and biochemical detection, reported in 2018
Now Purdue University researchers have discovered a two-dimensional nanomaterial that shows promise for high-speed electronics, defense tools and biochemical detection devices. It is predicted to change how infrared technology is used in national defense tools, surveillance equipment, high-performance electronics and biochemical detection devices.
The reliable production of two-dimensional (2D) crystals is essential for the development of new technologies based on 2D materials. However, current synthesis methods suffer from a variety of drawbacks, including limitations in crystal size and stability. The researchers created the nanomaterial based on Tellurium, which they called tellurene, in a solution. The material has a thin, durable structure with unique properties.
“We can build this material atom-by-atom and scale it up for many different uses,” said Wenzhuo Wu, an assistant professor in Purdue’s School of Industrial Engineering, who worked on the team that discovered tellurene. “Our material is superior to other two-dimensional materials such as black phosphorous because we have a high production yield and tellurene is air-stable. Tellurene can grow on its own without the help of another substance, which makes it different than those other materials.”
Tellurium is not abundant on the Earth’s crust, but Wu said only a tiny amount is needed to be synthesized through their solution method. Tellurene has several potential applications, including high-speed electronics and infrared technology. Wu said tellurene is ideal to incorporate into surveillance equipment and devices used by the government and military for national security and defense, including airport scanners, night-vision devices, infrared sensors and high-speed transistors.
“Our discovery is a nanomaterial with a very large lateral surface but atomic-level thickness,” Wu said. “It has a very strong light absorption component. We can develop state-of-the-art, ultrathin transistor and infrared devices using tellurene.”
Wu recently collaborated with Professor Peide Ye’s group from Purdue’s School of Electrical and Computer Engineering and demonstrated high-performance transistors using the tellurene material synthesized in Wu’s group. This work was recently published in Nature Electronics. Wu’s group is now working on the development of several tellurene based infrared technologies. Wu said tellurene’s thin structure also makes it more affordable and flexible compared with current bulky electronic devices.
“This new discovery also has potential applications in the field of biochemical detection,” Wu said. “For instance, tellurene could be used as a key building component for biosensors in airports to detect if a passenger is infected with a communicable disease. The tellurene is very sensitive to temperature differences in the body, which can be good indicators of disease.”
2D material for military
2D and heterostructured 2D materials have great potential for military applications in developing energy storage devices, sensors, electronic devices, armors and weapon systems. Advanced 2D material-based sensors and detectors provide high awareness and significant opportunities to attain correct data required for planning, optimization, and decision-making, which are the main factors in the command and control processes in the military operations. Moreover, advanced electronic devices such as processors or nano/microchips are essential to high-speed data and image processing, computing, and networking, especially to process and optimize big data.
2D materials can be used to develop cathodes having high power density, long-life and shorter start-up time for thermal batteries which
are employed for power delivering to electricity supply, electronic and activation systems of guided missiles, torpedos, and rockets. To date research interest and trends in material science and technology have not only focused on understanding the behavior of these materials at the nanoscale, but also under extreme conditions at the macro-scale.
2D materials are crystalline materials that consist of a single or a few layers of atoms and are used as superconductors for electronic devices either pure or combined with other 2D materials to improve their desired ability such as thermal and electric conductivity. Furthermore, some of them have good mechanical strength that is suitable for friction and wear reduction, which eventually increases the corrosion
resistance in tribological systems. Therefore, 2D materials can be used as solid lubricants for the application in micro and nano-electromechanical systems (MEMS/NEMS), which are used to develop chemical or biological sensors for detection of chemical gasses and biological agents in chemical and biological warfare, identification friend or enemy (FOE) systems, active surfaces, distributed sensor network, microrobotic electronic disabling systems.
With superior properties such as chemical inertness, thermal stability, electrical conductivity, oxidation resistance, and mechanical strength, graphene is the most promising 2D material for all application fields. Due to its higher mechanical strength than steel (tensile strength=0.4 GPa) with 130 GPa tensile strength, graphene has the potential to be a light ballistic armor material. In the case of the application of multi-layer graphene, on-body armors will increase the mobility of the soldiers in the operation field.
On the other hand, recent researches reported that hydrophobic graphene increases the corrosion resistance of the surfaces. Parasai, et al. reported that graphene significantly reduces the oxidation of the metals and it is the thinnest corrosion protective coating. With the high corrosion resistance, graphene can be used to protect critical parts of the mechanical or electronic systems from the corrosion that are used especially in naval operations, e.g. unmanned aerial vehicles (UAV) or air/surface radars, aircraft.
Due to its superconductivity, graphene can be used in electric/electronic applications as computer processors, antennas, and solar cells. On the other hand, quantum confinement and edge effects of graphene have been reported to cause photoluminescence (PL). Besides, by using quantum confinement effects, the fabrication size of quantum dots can be controlled to adjust the graphene bandgap and these dots have potential applications in a new generation of detection and microelectronics devices, biomedicine production. Its superior electrical property with low noise makes graphene an excellent sensor candidate that can be used in military applications such as pressure and humidity sensors.
The higher level of electrical conductivity and optical transmittance opens a path to graphene use in screens, liquid crystal displays, organic photovoltaic cells, and organic light-emitting diodes (OLEDs). Especially, shatter-resistant graphene-made screens and touch panels can be used in military applications in hard operating conditions. A very specific surface area with high conductivity is the desired characteristic
to develop electrodes for novel energy storage and batteries. Graphene has a very high specific surface area of 2675 m2 /g compared to metals.
Graphene is a supercapacitor material with a specific surface area of 925 m2 g-1, the pore size of mainly 3-15 nm, and a specific capacitance of 117 Fg−1 in H2 SO4 electrolyte. Therefore, graphene is used as an electrode material for lithium-ion batteries enhancing the anode’s conductivity in diverse phases of the charge-discharge cycle and capacity of the battery up to 1500 mAhg-1. Therefore, graphene increases battery storage capacity, which means longer battery life for handheld radios used by units in the operation field.
Graphene was used to produce infrared (IR) transparent windows that can be used in IR guided missiles. On the other hand, owing to higher than 85 % IR transmittance, graphene is used as an IR sensor/detector for IR cameras or missile detectors with desired electromagnetic (EM) shielding properties.
2D materials have been a strong candidate for optoelectronic device applications such as photodetectors, light-emitting diodes, and photovoltaic devices. Phototransistors, flexible thin-film transistors, IR detectors, electrodes for batteries, organic photovoltaic cells, and organic light-emitting diodes have been being developed from the 2D materials for devices that are used in weapon systems, chemical-biological warfare sensors, and detection systems
When looking at the mechanical properties of the 2D hBN, the tensile strength of the 2D hBN is reported to be 120-165 GPa, and Young’s modulus was found to be 0.8-1± 0.1 TPa by AFM indentation measurements. Due to this high mechanical strength and lower friction coefficient, it has been used as a solid lubricant in tribological systems or added into base oil as a nano additive in which it reduced wear approximately 50 %. The thermal conductivity of the few-layer 2D hBN nanosheet was measured to be 100-270 W/m.K, which is a good
heat spreading material for novel electronic devices. With these findings, it has been reported as a new material candidate against SiO2
used in transistors.
Although 2D hBN is an insulator material, it can be activated by graphene in fuel cells enhancing the cell performance up to 50%. On the other hand, with the high band edge absorption coefficient, it can be utilized to develop UV photodetectors.
2D MoS2 has been used to develop ultra-fast field-effect transistors (FETs), optical devices, and flexible electronic devices. Besides, the hybrid heterostructure MoS2 combined with graphene showed a good ability to sense gases. Thus, 2D MoS2 can be used to produce low-powered, high-performance gas sensors to detect and monitor expsive and chemical gases for land and marine units, especially, in chemical warfare84 . The 2D MoS2 has been used to develop phototransistors, flexible thin-film transistors, and electrodes for lithium-ion batteries. For the tribologic applications, single and multilayer MoS2 nanosheets were added into a base oil and tested with a ball on the disk tribometer. It was reported that multilayered or two-dimensional MoS2 nanosheets can be a commercial nano additive for the paraffin
oil to improve friction and wear resistance properties. Besides, 2D MoS2 was reported to be a good solid lubricant for relatively sliding mechanical components.
MXene 2D Materials have great potential to develop photothermal conversion, field-effect transistors, topological insulators, optoelectronic properties, sensors, and hydrogen evolution reactions. Furthermore, they have better saturable absorption (SA is up to 50%) than other 2D materials such as graphene and MoS2 (SA is up to 20%), which is used to increase modulation depth for optical isolator applications in fiber‐based femtosecond lasers. Therefore, they can be used in weapon systems such as FLIR cameras, targeting pods, especially they could be a solution to overheating of the laser power supply of targeting pods that cause missiles to fall into ballistic guidance.
Moreover, recent studies have been reported higher effective Young’s modulus of 330 ± 30 GPa than 2D MoS2 , GO, r-GO, however, lower
than graphene and hBN. This high elasticity suggests protective coatings, membranes, and nanoresonators for military applications.
Heterostructured 2D Materials
Graphene derived from exfoliation of the graphite is the flagship of the 2D materials researches and has also accelerated researches
on heterostructure 2D materials which are carried out directly stacking individual monolayers of 2D materials such as WSe2 , MoTe2, WS2 -MoS2, WSe2 -SnS2 , hBN-graphene, MoS2 -graphene. The combination of these 2D materials forms heterostructures that enable excellent electron transfer.
They also have specific properties that open new paths to novel researches for military applications including transistors, photodetectors, chemical, and biological sensors, and nanoelectromechanical systems. For example, the combination of graphene and black phosphorus provides rich novel light-substance interaction phenomena, like photothermoelectric, and various other optoelectronic effects which have the great potential to develop new IR detectors for military applications. Development of the flexible gas sensor by using MoS2 /graphene heterostructure material was reported by Cho, et al. With this sensor, hazardous/ toxic gases can be detected and it has potential usage in chemical gas detection systems for military applications.
Heterostructured 2D materials researches on developing energy storage systems have been significant in recent years to replace lithium-ion batteries with a new energy storage technology that has the ultimate fast charge capacity and long effective life. Graphene-based Na+, K+, Mg2+, and Al3 + electrodes are in the scope of this researches. Graphene-based silicene, borophene, phosphorene 2D heterostructures are
new electrode candidates for future energy storage devices.
The development of new energy storage devices can lead to an upgrade in the diesel-electric submarine propulsion system. Thanks to 2D heterostructure wearable sensing systems, flexible/stretchable electronics devices and novel sensors (pressure, humidity, etc.) could be developed for military applications to be used in infantry units. The Moire patterns (an involvement pattern produced by overlaying
similarly structured monolayer materials, but slightly rotated in any direction) are formed by 2D mono-layer van der Waals stacking materials such as MoS2 /MoSe2.
These materials with high electron mobility are reported to have great potential for the development of nanodevices. Therefore, the production of vertical or lateral heterostructures from two-dimensional materials opens a gate to quantumengineered transistors which will be the alternative silicon technology for sensors, electronic devices, and computers. Additionally, MXenes/graphene heterostructures have
been explored for battery cathodes and their positive effects on capacity compared to functionalized MXenes have been reported.
Challenges towards road to commercialization
However, the lab-to-fab transition lags behind expectations with slow commercial uptake. Academia and industry are still trying hard to develop reproducible and scalable ways for the synthesis of 2D materials, as well as for their characterization, processing and integration in application
A prerequisite for the deployment of 2D materials in applications is the ability to mass-produce them while ensuring satisfactory and reliable performance. Further improvements in controlling the manufacturing processes are certainly needed, and commercialization will also benefit from unified standardization of quality and performance, involving, for instance, an application-specific grading system for the materials produced.
The intrinsic properties and device performance of 2D materials are extremely sensitive to structural disorder that may be generated during synthesis or processing — reproducibility on a large scale can thus hardly be achieved without structural control at the nanoscale. The development of encapsulation strategies and cleaner device fabrication techniques has brought remarkable performance improvement, yet more work is needed to reveal remaining unknown disorder sources, further reduce intrinsic and extrinsic disorder, and scale up these techniques.
Moving forward, the next step towards commercialization of devices — particularly optoelectronic devices, where proof-of-concept prototypes based on 2D materials have shown potential to outperform commercial competitors — would be the integration of them with materials and processes well entrenched in the industry. The integration of these materials in the Si production line may offer a promising and convenient direction to both take advantage of 2D materials’ superior properties and extend the functionalities of currently available Si complementary metal–oxide–semiconductor platforms devices, without requiring substantial changes in fabrication facilities and processes.
‘Suit of armour’ protects 2D materials for new-gen electronics, reported in Feb 2021
An international team of scientists has invented the equivalent of body armour for extremely fragile quantum systems, which will make them robust enough to be used as the basis for a new generation of low-energy electronics. Protection is crucial for thin materials such as graphene, which are only a single atom thick – essentially two-dimensional (2D) – and so are easily damaged by conventional layering technology, said Matthias Wurdack, who is the lead author of the group’s publication in Advanced Materials. The scientists applied the armour by gently squashing droplets of liquid metal gallium onto the materials, coating them with gallium oxide.
“The protective coating basically works like a body armour for the atomically-thin material, it shields against high-energy particles, which would cause a large degree of harm to it, while fully maintaining its optoelectronic properties and its functionality,” said Mr Wurdack, a PhD student in the Nonlinear Physics Centre (NLPC) of the Research School of Physics, and the FLEET ARC Centre of Excellence. The new technique opens the way for an industry based on ultra-thin electronics to expand, said leader of the research team, Professor Elena Ostrovskaya, also from NLPC and FLEET.
The team created their protective layer by exposing to air a droplet of liquid gallium, which immediately formed a perfectly even layer of gallium oxide on its surface a mere three nanometers thick. By squashing the droplet on top of the 2D material with a glass slide, the gallium oxide layer can be transferred from the liquid gallium onto the material’s entire surface, up to centimetres in scale.
“2D technology could also enable super-efficient sensors on space craft, or processors in Internet of Things devices that are less limited by battery life.” However, this work promises lower-energy alternatives for electronics and optoelectronics, by harnessing the superior performance of 2D semiconducting materials, such as tungsten disulphide, which was used in this study.
Because this ultrathin gallium oxide is an insulating amorphous glass, it conserves the optoelectronic properties of the underlying 2D semiconductor. The gallium oxide glass can also enhance these properties at cryogenic temperatures and protects well against other materials deposited on top. This allows the fabrication of sophisticated, layered nanoscale electronic and optical devices, such as light emitting diodes, lasers and transistors.
2-D Materials Market
2D materials or 2-Dimensional materials are defined as materials that are crystalline and consist a single layer of atoms. 2D materials can generally be categorized into either 2D allotropes of various elements or compounds as a suspension of graphite oxide with atomic planes. Properties such as conductivity of heat and electricity, corrosion resistance, optically transparent, and flexibility makes 2D materials ideal for usage in electronics and semiconductor industries.
Inclination for usage of renewable energy, rise in usage of 2D materials in hydrogen fuel cells in electric cars, cost saving initiatives, environmentally-friendly norms, and pollution-free legislations by governments are the major drivers of the 2D materials market. Increase in demand for Transparent Conductive Films (TCF) in electronic devices such as touch screens of mobile phones, displays, solid state lighting, and solar PV modules is another key factor boosting the 2D materials market.
Significant investments by emerging economies such as India, China, and Japan in sectors such as transport, energy storage, composites, textiles, and others is also one of the prominent factors augmenting the 2D materials market. Factors such as development of cost-effective graphene (2D Materials) electrodes and requirements to meet industrial norms are hampering the 2D materials market.
Based on type, the market can be segmented into graphene, graphyne, borophene, germanene, silicine, and stanene. Graphene, a monolayer material derived from graphite, is a crystalline allotrope of carbon. It is relatively stronger than most steels by weight. Graphene is the widely used 2D material due to its extensive range of applications in various sectors.
The market for graphene has grown hugely in the past decade, with numerous products now on the market and more to come as graphene producers record steadily increasing revenues and OEMs witnessing significant returns in clothing, sportswear, footwear, tires, batteries etc. Graphene is attracting increasing attention from investors, researchers and industrial players due to exceptional mechanical, electronic, and thermal properties. Graphene is available in multi-ton quantities from many producers and has been identified by many industry sectors as a key materials that will drive future product development in flexible electronics, smart textiles, biosensors, drug delivery, water filtration, supercapacitors and more
In terms of end-use, the 2D materials market can be divided into pharmaceuticals, photovoltaic, semiconductors, automobile, airplanes, electronics, and energy storage devices. 2D materials are increasingly used in energy storage devices such as super capacitors, fuel cells, and rechargeable batteries. Automobile and electronics segments are expected to witness significant growth from 2017 to 2025. Rise in usage of 2D materials in automobile, airplanes, and electronics industries to lower manufacturing cost and time is the primary factor driving the segments.
In terms of geography, the 2D materials market can be segregated into North America, Latin America, Europe, Asia Pacific, and Middle East & Africa. Asia Pacific is the fastest growing region of the 2D materials market; China accounts for the largest graphite reserves in the world. The country is currently the largest producer of graphene in the world. In terms of consumption, China and Japan are the major consumers of graphene, as it is used to replace lithium ion batteries in electric cars. Replacement of traditional lithium ion batteries with graphene helps companies lower the charging period of electric cars, thus saving costs, time, and increasing efficiency. With vast base of R&D and technological innovations, China is one of the fastest growing markets for producing solar PV modules using graphene.
Segmentation by Application: Semiconductor, aerospace, consumer electronics, healthcare, and energy among others.
Some of the major players in Global 2-D Materials Market include 2-D tech (U.K.), ACS materials (U.S.), Planar Tech (U.S.), Garmor (U.S.), Thomas-swan (U.K.), and Nitronix (U.S.) among others.