lighting - Page 6

The National Graphene Institute was recently opened in the UK, in an official ceremony that also included another intriguing event.

Professor Sir Kostya Novoselov demonstrated to the Chancellor of the Exchequer George Osborne the graphene light bulb, which was mentioned to be set to launch later in 2015. While the price is yet unknown, it is rumored to be relatively low-price, cut energy use by 10% and last longer owing to its conductivity.

Researchers from the Chinese Jilin University, along with Louisiana State University, succeeded in making graphene-enhanced quantum dot-light emitting diodes (QD-LEDs). They fabricated QD-LEDs which show better current efficiency and power efficiency than similar ITO-based devices working at a low current density. The result indicates that graphene can be used as anodes to replace indium tin oxide (ITO) in QD-LEDs.

Single layer graphene was introduced as an electrode into the QD-LED. Graphene-based QD-LEDs performed as well as ones based on ITO anodes and the maximum brightness could meet the minimum brightness requirement of display applications. It demonstrates that single-layer graphene film has great potential to be used in QD-LEDs as an anode. The researchers are now focusing on searching for higher efficiency QDs and optimizing device structures to further improve the efficiency.

In November 2014, James Baker, business director at the UK's National Graphene Institute (NGI), declared a LED light factory about to be opened in Manchester by an unnamed company, in which graphene will be used to dissipate heat.

Now, in a statement given at the Insider's Property Investment Forum in London, Baker mentioned that graphene lightbulbs will be available for purchase in B&Q within the next six months. While Baker did not offer any additional details regarding the identity of the supplier or even confirmed that this product will come from the afformentioned factory, this is still a very interesting mention.

Researchers at the University of Manchester (led by Novoselov, one of the original isolators of graphene and Nobel winner) and University of Sheffield have developed a prototype of a semi-transparent graphene-based LED device that could lay the foundation for flexible screens, to be used in next-gen mobile phones, tablets and TVs. This extremely thin display (about 10-40 atoms thick) was created using sandwiched "heterostructures" and emits a sheet of light across its entire surface.

The 2D LED comprises of metallic graphene, hexagonal boron nitride and various semiconducting monolayers. This prototype shows that graphene (combined with other flexible 2D materials) is not just limited to simple electronic displays, but could be exploited to create light emitting devices that are thin, flexible, semi-transparent and intrinsically bright.

Reseachers from the University of Sydney managed to create graphene quatum dots that shine nearly five times brighter than regular dots. These powerful dots can be used for bio-imaging, like capturing images of internal organs or be injected into the body to detect cancer cells. They are even much less toxic compared to current dots for internal use. Other possible uses include ultra-bright LEDs, like the ones in screens or signs, or even batteries with long-life and faster charging times.

The researchers used ultrasound to break graphene sheets into atom-scale dots, then used potassium hydroxide to enhance the surface area of these dots. They increased the surface area by six times to get the dots to fluoresce almost five timer brighter than conventional dots. 

James Baker, business director at the National Graphene Institute (NGI) in the UK said a technology company (that remained unnamed) is about to open a LED light factory in Manchester.

The factory will produce LED lighting in which graphene will be used to dissipate heat, thanks to its superior heat conductivity trait. 

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 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.

The Graphene Research Centre (GRC) at the National University of Singapore (NUS) and BASF announced a new partnership to develop the use of graphene in organic electronics devices - such as OLED devices. The goal of this collaboration is to interface graphene films with organic electronic materials, with an aim to create more efficient and flexible lighting devices.

In this collaboration, the GRC will contribute its graphene knowledge (the synthesis and characterization of the graphene) while BASF is focused on organic materials. Of course BASF is also engaged with graphene research (for several years) and are looking to speed up their device development with this new partnership.

Korean researchers have developed a new blue nitride LED that uses 3D graphene foam as a transparent conductor for the p-contact. They say that the graphene foam reduced the forward voltage by 26% and increased the light output by 14%.

The researchers used commercial 3D graphene foam, produced on 3D copper foam using chemical vapor deposition. The graphene foam on copper was then spin-coated with PMMA and the copper etched away (using ammonium sulfate). The graphene foam was cut into a square and transferred to the p-type gallium nitride layer of a commercial blue LED.