Transparency - Page 3

An international team of scientists, including ones from the University of Exeter, the Institute for Systems Engineering and Computers, Microsystems and Nanotechnology (INESC-MN) in Lisbon, the Universities of Lisbon and Aveiro in Portugal and the Belgian Textile Research Centre (CenTexBel) designed a new technique for embedding transparent and flexible graphene electrodes into fibers commonly used in the textile industry.

This could lead the way to creating wearable electronic devices such as clothing containing computers, phones and MP3 players, which are lightweight and durable. The scientists state that the possibilities for its use are endless, including textile GPS systems, biomedical monitoring, personal security or even communication tools for the sensory impaired.

Researchers at the University of Guangzhou, China, managed to improve the capacitance of supercapacitors by nearly 1000-fold compared with that of the laminated or wrinkled CVD graphene-film-based supercapacitors. To achieve this, the researchers integrated transparency into freestanding, flexible graphene paper (FFT-GP). These supercapacitors's capacitance is also about ten times better than previously reported values for transparent and flexible supercapacitors based on pure carbon materials. However, some carbon-based nontransparent supercapacitors still perform better than the FFT-GP-based transparent supercapacitor. 

The improved performance is mainly based on the prism-like graphene building blocks that the FFT-GP is made of. The hollow structures of the graphene that give the material its transparency also provide additional space for chemical reactions to occur compared to other materials. Also, the aligned and interconnected prism-like structures provide a wide open path for ions and electrons to travel along and the good charge transport leads to an overall better performance.

Researchers from University of Wisconsin (with support from DARPA) developed new 4-atom thick graphene-based sensors that are so thin to be virtually transparent - which allows the sensors to perform both electrical and optical brain measurements at the same time.

The graphene-based contacts are used to measure and also stimulate neural tissue. These kinds of sensors could provide new insights into relationships between brain structure and function, and how these evolve by injury or disease.

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 MIT developed a flexible transparent graphene-based electrode for graphene polymer solar cells (PSC). They report that this is the most efficient such electrode ever developed, with power conversion efficiencies of 6.1% (anode) and 7.1% (cathode).

To achieve the record efficiencies, the researchers thermally treated the MoO3 electron blocking layer and directly deposited a ZnO electron transporting layer on the graphene. The researchers say that the process is simple and reproducible.

Researchers discovered that lithium-doped graphene sheets (3-60 layers in thickness) result in the highest ever sheet resistance and transmittance ever reported for continuous thin-films. This may prove to be an important step towards an ITO replacement for touch panels and solar cells.

The lithium was inserted between the graphene layers. As a result of this electrochemical intercalation, the Fermi level is upshifted by the doping effect, resulting in a more transparent and conductive material.

Researchers from Philips, Graphenea and the University of Cambridge developed a monochrome OLED device that uses graphene as the transparent conductor layer. They report that the graphene-based TC outperforms that state-of-the-art ITO solutions currently used for OLED panels.

ITO is the most popular material for transparent conductors in displays and solar cells, but it is expensive, rare and brittle, and a lot of companies are developing alternatives - based on silver, carbon or other materials.

Researchers from the University of Manchester are developing a new graphene-latex composite for use in condoms. The researchers hope that graphene will enable thinner, stronger and safer condoms - which makes sense as graphene is very thin and light but yet strong, transparent and flexible. The researchers have been awarded £62,000 ($100,000) by the Bill and Melinda Gates Foundation.

The researchers say that the new composite material will be "tailored to enhance the natural sensation during intercourse while using a condom, which should encourage and promote condom use".

The EU launched a new project called GLADIATOR (Graphene Layers: Production, Characterization and Integration) that aims to improve the quality and size of CVD graphene sheets and reduce the production cost.

GLADIATOR directly targets the transparent electrodes market and will demonstrate that ITO can be matched on performance (over 90% transparency and a resistance of less than 10 W/sq) and cost (under 30 €/m²). During the project, they will produce ultraviolet organic photodiodes and large area flexible OLEDs.

The University of Cambridge released (this was towards the end of August 2013, but I just found it now) a video showing sample transparent graphene electrodes based device prototypes:

In the video you can see a graphene touch panel used in a simple digital piano application, and also a flexible transparent display. The keyboard device is simple - when you touch the graphene electrode, the electrical charge changes which is detected by a simple electronic circuit-board connected to a speaker.