A quick look at the seven popular materials in 2020

Since the 18th century, materials science has been the foundation of engineering disciplines. Most of the innovations, innovations, and inventions in the world depend on the development and progress of materials science. Without materials science, there would be no development of a series of high-tech products such as airplanes, automobiles, computers, and smartphones. Benjamin Stafford, the material science editor of Matmatch, released an analysis of cutting-edge research topics in the field of materials science 2020 in May 2020. The seven hot materials science research topics in 2020 summarized by him are:

Graphene

Perovskites

Materials informatics

Selective laser sintering

Metamaterials

Dichalcogenides

Topological insulators

Almost all universities in the world with science and engineering research have related courses or faculties dedicated to the above topics. Among the themes mentioned above, Benjamin, the material science editor of Matmatch, believes that some of these themes may become the promoters of the next generation of major innovations. Just as the discovery of semiconductors brought us into the computer age, perhaps memristors or topological insulators will bring us into the next paradigm shift in quantum computers; transition metal dihalides may open up new applications for optoelectronic devices; metamaterials may Uncover the invisible secret...

This article analyzes thousands of publications from ScienceDirect and reveals the latest research trends in the field of materials science in 2020.

1 Graphene

As of 2019, graphene has the largest number of publications, exceeding 20,000. Since 2009, in the inventory of the world's thinnest materials, graphene has often received media attention. However, according to the above statistics, although graphene's publication volume is growing strongly every year, its growth rate has declined slightly. This is mainly due to the gradual understanding of graphene materials by scientists and scholars and the maturity of their performance. The research is gradually transitioning to the stage of looking for preparation methods for large-scale production of graphene. At the same time, researchers are also introducing some interesting new applications in graphene, such as sensors, drugs, composite materials, batteries, coatings, electronic products, textile products, automotive applications, transistors, etc.

2 Perovskite

Perovskite materials have the chemical formula ABX3 and cubic crystal structure, where "A" and "B" are metals, and "X" is usually oxygen, including a series of semiconductor and insulator materials used in various devices and technologies.

In fact, every electronic device manufactured today contains some kind of perovskite in its capacitors, sensors, LEDs, or other components. The application of perovskites is so common because they provide a series of useful optical and electrical properties, such as dielectric properties, piezoelectric properties, high-efficiency luminescence properties in LEDs, and photovoltaic power generation properties.

Since 2012, peoples interest in perovskite solar cells has surged. People realize that if perovskite is used rationally, solar cells may achieve higher power generation efficiency than at the time. In 2009, the highest efficiency of perovskite solar cells was recorded at 3.8%, and by 2018, this record had increased to 23.3%. Perovskite-based solar cells have excellent light absorption, charge carrier mobility, and low manufacturing costs, making them a strong competitor to provide low-cost solar cells.

Current research on perovskite is focused on improving its chemical stability to extend its service life. Unlike silicon photovoltaic cells processed from silicon ingots, the perovskite absorber layer can be printed or spin-coated, making its production cost cheaper. In addition, silicon materials are very sensitive to manufacturing defects, but perovskite-based batteries perform better in this regard. Once perovskite-type photovoltaics have better long-term stability, they are expected to become the main alternative products for silicon-based solar technology.

3 Material Informatics

Materials informatics is a combination of materials science and informatics, which aims to help scientists realize the selection, development, and use of materials through the means of big data information science. In other words, "material informatics" is a novel data-driven technology that combines the basic knowledge of materials and experimental data with advanced statistical models to predict future material properties. Since the early 2000s, this has been an emerging field, and with higher computing power and a better record of experimental data, it will grow exponentially.

With the help of powerful computing capabilities, such as machine learning or material simulation, some manual experiments can be replaced. This not only saves time and cost but also further liberates the labor force, enabling scientists and scholars to come up with more innovative ideas and experimental plans. By then, most of the time-consuming or error-prone experiments will be done by machines. The simulation is complete. At the same time, a large amount of data will provide scientific research workers with new ideas and realize a virtuous circle as a whole.

Means such as machine learning or simulation will not completely replace empiricism. Its development does not mean that we can abandon the benefits of manual experiments, but should give full play to their respective advantages. The combination of the two can make the development of materials science more rapid.

4 Selective laser sintering

Selective laser sintering (SLS) is a method used for additive manufacturing (3D printing), mainly for metal and polymer materials. Just like material informatics, the huge impact of digitalization on manufacturing is well known, so additive manufacturing is regarded as an important development direction of the fourth industrial revolution.

Selective laser sintering, as additive manufacturing technology, uses the laser as a power to sinter powder materials, automatically aligns the laser to the spatial point defined by the 3D model, and binds the materials together to create a solid three-dimensional structure. It is similar to selective laser melting. The two are examples of the same concept, but the technical details are different. They are mainly used for rapid prototyping and small-batch production of parts, which can realize rapid prototyping with complex geometric structures.

SLS technology can use materials such as metals, thermoplastics, ceramics, or glass for printing. Most of the commercially available materials are in powder form, including but not limited to polymers, such as polyamide (PA), polystyrene (PS), and polycarbonate. (PC), thermoplastic elastomer (TPE) and poly aryl ether ketone (PAEK), etc. Polyamides are the most commonly used SLS materials because they have ideal sintering properties as semi-crystalline thermoplastics, and therefore the parts also have ideal mechanical properties.

5 Dichalcogenide

Between 2017 and 2018, the appearance rate of bischalcogenides in scientific publications increased by 54%. It is a material with an MX2 arrangement, where M is a transition metal atom (such as Mo, W, Ti, V, and Nb). ), X is a chalcogen atom (S, Se or Te). Scientists are mainly interested in it that they can be made into a single layer similar to graphene, which has potential applications as superconductors and semiconductors.

The transition metal-carbon disulfide (TMD or TMDC) monolayer is an atomically thin semiconductor of the MX2 type, where M is a transition metal atom (Mo, W, etc.), and X is a chalcogen atom (S, Se, or Te). A layer of M atoms is sandwiched between two layers of X atoms. They are part of the so-called 2D material family. The name is mainly to emphasize they're extraordinary thinness. For example, the thickness of a single layer of MoS2 is only 6.5Å. The key feature of these materials is that compared with the first row of transition metal-carbon disulfide, the interaction of large atoms in the two-dimensional structure, such as WTe2, exhibits exceptional giant magnetoresistance and superconductivity.

In 2011, the media reported the first field-effect transistor (FET) made of a single layer of MoS2. Due to the excellent static control of the conduction in the 2D channel, it has an excellent on/off ratio at room temperature, exceeding 108. Since then, FETs made of MoS2, MoSe2, WS2, and WSe2 have been made, and their very thin structure makes them promising for thin and flexible electronic products.

6 metamaterials

Metamaterials are man-made materials designed to have characteristics that are not found anywhere in nature. Their main applications include antenna materials, absorber materials, superlenses, invisible devices, seismic protection, sound filtering, etc.

Metamaterials have some special properties, such as allowing light and electromagnetic waves to change their inherent properties, and such effects cannot be achieved by traditional materials. There is nothing special about metamaterials in terms of composition. Their peculiar properties stem from their precise geometric structure and size.

Metamaterials are an interdisciplinary subject, including electronic engineering, condensed matter physics, microwaves, optoelectronics, classical optics, materials science, semiconductor science, and nanotechnology. Its singular nature makes it have a wide range of application prospects, such as high-receiving antennas, radar reflectors, earthquake warnings, etc.

7 Topological insulator

According to the different conductive properties, materials can be divided into two categories: "conductors" and "insulators". Furthermore, according to the different topological properties of electronic states, "insulators" and "conductors" can also be divided into more detail. Topological insulators are a type of insulators that are differentiated from other ordinary insulators based on this new standard.

A topological insulator is a kind of internal insulation, and the interface allows the charge to move. Therefore, the body of a topological insulator is the same as the generally recognized insulator, which is insulated, but there is always a conductive edge state on its boundary or surface, which is the most unique property different from ordinary insulators. Such a conductive edge state is stable under the premise of ensuring a certain symmetry (such as time-reversal symmetry), and the direction of movement of conductive electrons with different spins is opposite, so information can be transmitted through the spin of the electrons. , Unlike traditional materials to pass through the charge.

As a new quantum state of matter, the discovery of topological insulators is considered the "Next Big Thing" after graphene. Topological insulators have great value in understanding basic physics and the application of semiconductor devices, so they have gradually become a research hotspot in the field of condensed matter physics and electronics, attracting the attention of scientists around the world, in order to solve the problem of the imminent failure of Moore's law and break energy and information. Bottlenecks are faced by other fields. After more than ten years of in-depth research, topological insulators have made significant progress in theoretical foundations, material systems, preparation methods, physical properties, and new application development. The ultra-wide frequency response from infrared to terahertz frequency bands makes topological insulators attractive application prospects in microelectronics, optoelectronics, and spintronics.