Application areas of graphene

1. Integrated circuit

Graphene possesses desirable properties as an excellent integrated circuit electronic device: high carrier mobility and low noise. In 2011, IBM succeeded in creating the first graphene-based integrated circuit - a broadband wireless mixer, which handles frequencies up to 10 GHz and whose performance is unaffected at temperatures up to 127°C. Graphene nanoribbons have the characteristics of high electrical conductivity, high thermal conductivity, and low noise, and are a choice of interconnect materials for integrated circuits, with the potential to replace copper metal. Some researchers have tried to make quantum dots out of graphene nanoribbons. They change the width of the nanoribbons at specific locations to form quantum confinement. The low-dimensional structure of graphene nanoribbons possesses very important optoelectronic properties: population inversion and broadband optical gain. These excellent qualities enable graphene nanoribbons to be placed in microcavities or nanocavities to form lasers and amplifiers. Studies have shown that graphene nanoribbons can be applied to optical communication systems, and graphene nanoribbon lasers can be developed.

2. Graphene transistors

In 2005, Geim's research group and Kim's research group found that graphene has a high carrier mobility 10 times that of commercial silicon wafers at room temperature, and is little affected by temperature and doping effects, showing room temperature sub-micron scale ballistic transport properties (up to 0.3 m at 300 K), which is the most prominent advantage of graphene as a nanoelectronic device, make room-temperature ballistic FETs very attractive in the field of electronic engineering possible. The large Fermi speed and low contact resistance help to further reduce the device switching time, and the ultra-high frequency operating response characteristics are another significant advantage of graphene-based electronic devices. With modern technology, graphene nanowires can prove generally capable of replacing silicon as a semiconductor.

3. Transparent conductive electrodes

The good electrical conductivity and light transmission properties of graphene make it have a very good application prospect in transparent conductive electrodes. Touch screens, liquid crystal displays, organic photovoltaic cells, organic light-emitting diodes, etc., all require good transparent conductive electrode materials. In particular, the mechanical strength, flexibility, and light transmittance of graphene are superior to those of the commonly used material, indium tin oxide. By chemical vapor deposition, a large-area, continuous, transparent, high-conductivity few-layer graphene film can be made, which is mainly used in the anode of photovoltaic devices, and achieves an energy conversion efficiency of up to 1.71%; Compared with the element made of indium tin oxide material, it is about 55.2% of its energy conversion efficiency.

4. Thermally conductive material/thermal interface material

Studies have shown that the thermal conductivity (K) of graphene at room temperature has exceeded the limit of bulk graphite (2000 W/m•K), carbon nanotubes (3000~3500 W/m•K) and diamonds. It reaches 5300 W/m•K, far exceeding metal materials such as silver (429 W/m•K) and copper (401 W/m•K). Excellent thermal conductivity and mechanical properties make graphene have great potential for development in the field of thermal management. Graphene-based films can be used as flexible heat sink materials to meet the heat dissipation requirements of high-power, high-integration systems such as LED lighting, computers, satellite circuits, laser weapons, and handheld terminal equipment. These research results provide a new perspective for the design of structural/functional integrated carbon/carbon composites.

5. Sensors

The unique two-dimensional structure of graphene makes it have bright application prospects in the field of sensors. The huge surface area makes it so sensitive to the surrounding environment that even a gas molecule adsorption or release can be detected. This detection can currently be divided into direct detection and indirect detection. The adsorption and release processes of single atoms can be directly observed by transmission electron microscopy. The adsorption and release processes of single atoms can be indirectly detected by measuring the Hall effect. When a gas molecule is adsorbed on the graphene surface, a local change in resistance occurs at the adsorption site. Of course, this effect can also occur in other substances, but graphene has the good quality of high conductivity and low noise, which can detect this small resistance change.

6. Supercapacitors and Lithium-Ion Batteries

Due to its exceptionally high surface area to mass ratio, graphene can be used as a conductive electrode for supercapacitors. Scientists believe that the energy density of such supercapacitors will be greater than that of existing capacitors. Due to its good conductivity and huge specific surface area, graphene can be widely used in lithium-ion batteries: it can be directly used as anode material of lithium-ion batteries, or it can be compounded with SnO2, Si and other materials as anode material of lithium-ion batteries. The modification of graphene can effectively shorten the charging time of Li-ion batteries and increase the power density of Li-ion batteries.

7. Solar cells

As an important material for organic solar cells (OPV cells). In 2010, a new type of solar cell combining graphene and silicon was constructed for the first time. In this facile graphene/silicon model, graphene not only acts as a transparent conductive film, but also can separate photogenerated carriers at the interface. This structure, which can be combined with conventional silicon materials, opens up new research directions for advancing graphene-based photovoltaic devices.

8. Graphene Biodevices

Due to its modifiable chemical functions, large contact area, atomic-scale thickness, molecular gate structure, etc., graphene is an excellent choice for bacterial detection and diagnostic devices. Scientists hope to develop a fast and inexpensive technology for rapid electronic DNA sequencing. They see graphene as a material with this potential. Basically, they want to make a nanohole about the width of DNA out of graphene, and let DNA molecules swim through the nanohole. Since the four bases (A, C, G, T) of DNA will have different effects on the conductivity of graphene, as long as the small voltage difference generated when the DNA molecule passes through, you can know which base is Swim through the nanohole.

9. Antibacterial substances

Scientists from the Shanghai branch of the Chinese Academy of Sciences have found that graphene oxide is super effective at inhibiting the growth of E. coli without harming human cells. If graphene oxide is also antibacterial to other bacteria, it could find a range of new applications, like shoes that automatically remove odors, or packaging that preserves the freshness of food.

10. Graphene photosensitive element

Nanyang Technological University in Singapore has developed a new type of photosensitive element using graphene as the material of the photosensitive element. It is expected that through its special structure, the photosensitive element has a photosensitive ability 1,000 times better than that of traditional CMOS or CCD, and the energy consumption is only 1/10 of the original required. Like many new sensor technologies, this technology will initially be used in monitors and satellite imagery.

11 Desalination

Research shows that graphene filters may outperform other desalination technologies by a large margin. By precisely controlling the pore size of porous graphene and adding other materials to it, the properties of the edges of the graphene pores can be altered to repel or attract water molecules. In this way, the specially made graphene acts like a sieve to quickly filter out salt from seawater, leaving only water molecules behind. The key to the desalination process is very precise control of the size of the graphene pores.