KAIST

A KAIST research team has developed a graphene-based hybrid storage device with power density 100 times faster than conventional batteries, allowing it to be charged within a few seconds. The team states that it could be suitable for small portable electronic devices.

Porous metal oxide nanoparticles formed on graphene in the aqueous hybrid capacitor. (Image: KAIST)

The researchers developed an aqueous hybrid capacitor (AHC) that boasts high energy density, high power, and excellent cycle stability by synthesizing two types of porous metal oxide nanoclusters on graphene to create positive and negative electrodes for AHCs.

Researchers at the Institute for Basic Science (IBS, South Korea), in collaboration with teams from the University of Birmingham and the Korea Advanced Institute of Science and Technology (KAIST), have developed unique graphene-based lenses with tunable features. These optical devices, made of graphene and a punctured gold surface, could become optical components for advanced applications like amplitude tunable lenses, lasers (i.e. vortex phase plates), and dynamic holography.

The scientists explain that metasurfaces are new 2D materials that can effectively control the electric and magnetic components of light (and other electromagnetic waves) and bend them to chosen directions. Controlling the beam's direction can bring out interesting phenomena; the most incredible being the "invisibility cloak effect", where light waves bypass an object recreating the image beyond the object.

Researchers at the Institute for Basic Science (IBS) and KAIST have designed a graphene synthesis mechanism using laser-induced solid-state phase separation of single-crystal silicon carbide (SiC). According to the scientists, the laser material interaction technology can be a powerful tool for the next generation of 2D materials.

Using molecular dynamic simulations and high resolution microscope images, the researchers discovered that a single-pulse irradiation of xenon chloride excimer laser of 30 nanoseconds melts SiC, causing the separation of a liquid SiC layer, a disordered carbon layer with graphitic domains (approximately 2.5 nm thick) on the top surface and a polycrystalline silicon layer (roughly 5 nm) below the carbon layer. The sublimation of the separated silicon is caused when additional pulses are given, while the disordered carbon layer is changed into a multilayer graphene.

Researchers at Korea Advanced Institute of Science and Technology (KAIST) have developed a new graphene oxide-based speaker design said to be specifically targeted for the mobile audio market. The speaker does not require an acoustic box to produce sound.

The researchers used graphene in a relatively simple, two-step process that yielded a thermoacoustic speaker. Thermoacoustics is based on the idea that sound can be produced by the rapid heating and cooling of a material instead of through vibrations.

Researchers from Korea Advanced Institute of Science and Technology (KAIST) have fabricated light-emitting diodes (LEDs) based on graphene quantum dots (GQDs). The researchers made pure GQDs using a cost-effective, scalable and environmentally friendly method that allows direct fabrication of GQDs using water, without surfactants or chemical solvents.

Those GQDs were then used as emitter material to create an OLED device.The scientists constructed GQD LEDs exhibiting luminance of 1000 cd/m2, which is well over the typical brightness levels of the portable displays used in smartphones.

Researchers at the Korea Advanced Institute of Science and Technology (KAIST) managed to create durable artificial muscles using a graphene electrode. Ionic polymer metal composites (IPMCs), or artificial muscles, change in size or shape when exposed to electric fields and could be extremely useful in the fields of robotics and prosthetics. 

IPMC motors, (referred to as actuators), are created from a molecular membrane that is stretched between two metal electrodes. Upon applying an electric field, a redistribution of ions is caused that forces the structure to bend. These structures do not consume a lot of power and are able to mimic life-like motions. These devices, however, have a number of disadvantages like cracks that form on the metal electrodes and cause ions to leak through the electrodes and reduce performance. A possible solution to this problem is embodied in the researchers' thin electrode, based on an ionic polymer-graphene composition (IPGC). These new electrodes repel water and are very resistant to cracking. They also have a robust inner surface that allows the migration of ions within the membrane to cause bending.

Researchers at the Korean KAIST developed a technique for the delamination of single-layer graphene from a metal etching, that enables different types of transfer methods such as transfer onto a surface of a device or a curved surface, and large surface transfer onto 4 inch wafers. This method could be helpful for wearable smart gadgets and various graphene electronic devices.

While the traditional method of wet transfer might harm or contaminate the graphene in the process, this technique grants safer transfer as well as significant freedom in the transfer process. After a graphene growth substrate formed on a catalytic metal substrate is treated in an aqueous PVA solution, a PVA film is formed and a strong adhesion force is formed between the substrate and the graphene layers. The graphene is delaminated from the growth substrate by means of an elastomeric stamp while the graphene layer is in an isolated state and thus can be freely transferred onto a circuit board.

Researchesr from Korea's Ulsan, KAIST and ETRI institutes developed a process that produces flexible transparent graphene electrodes that can be attached to the skin (or any kind of delicate object). This could enable applications such as electronic tattoo-like stickers or bio-signal sensors.

A graphene metal fiber composite ise used, which lowers the resistance of the transparent electrode to approximately 1/20th of existing ones. This enables the electrodes to be used in flexible displays or sensors. The new process is similar to a widely-used semiconductor process which means that this can be scaled commercially.

Researchers from the Korean's KAIST institute developed a new process to produce graphene quantum dots that are equal in size and highly efficient in emitting light. Quantum Dots potentially can be used to develop emissive flexible displays (similar to OLED displays), and this development may enable those displays to be graphene-based.

The process involves mixing salt, water and graphite and then synthesizing a chemical compound between layers of graphite. All the resulting quantum dots were 5 nanometer in diameter, and these QDs do not contain and heavy metals (like current commercial quantum dots). The process is reportedly easy to scale and should not be expensive.

Researchers at from Korea's KAIST institute developed a new method to fabricate defect-free graphene. Using this graphene, they developed a promising high-performance anode for Li-Ion batteries.

The method starts with a Pyrex tube and fill it with graphite powder. The open-ended tube is placed in another, larger tube and potassium is added to the gap between the tubes. The tubes are sealed and heated - which causes the potassium to move inside the micropores in the graphite powder - creating a potassium-graphite compound. This is placed in a pyridine solution, which expands the layer and separates them to form graphene nanosheets - which are then exfoliated to create a single graphene sheet.