HKUST is revolutionising display and optoelectronic technologies

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By Andy Wong

Can you imagine being able to use your smartphone continuously for nine days after a single charge, with its power consumption reduced by 80 per cent? How about a liquid crystal display (LCD) which is many times better than what you can see today?  If you work at the Hong Kong University of Science and Technology (HKUST), such leaps of the imagination are an everyday occurrence.

“We make every effort to revolutionise green display and optoelectronic technologies, and work hard to turn impossibilities into possibilities,” says Hoi Sing Kwok, the Dr William MW Mong chair professor of nanotechnology, and chair professor of electronic and computer engineering at HKUST.

An expert in display technologies, energy, and photonics, Kwok was appointed the director of the state key laboratory on advanced displays and optoelectronic technologies (SKL) at HKUST when it was established in September 2013.  The SKL was formed in collaboration with the mainland’s Sun Yat-sen University, following approval from the central government’s Ministry of Science and Technology.  The aim is to develop energy-saving displays and world-changing optoelectronic applications.

The SKL also provides training programmes and short courses for Chinese enterprises, and holds seminars and international conferences with institutions for technology exchange.

Ching Wan Tang, IAS Bank of East Asia professor at the HKUST Jockey Club Institute for Advanced Study, and the chair professor at the department of electronic and computer engineering, department of chemistry and department of physics, is another key member of the SKL. The duo has helped over 100 PhD students to push the frontiers of technological research, and thereby produce the most advanced and comprehensive research and development results in Hong Kong and the mainland. Over 90 patents have been achieved so far.

Kwok and Tang are both globally recognised scientists. Kwok was recently appointed the chairman of the Society of Information Display’s International Symposium 2016, which takes place in San Francisco. He is the first person of Chinese descent from China to be invited to take up the chairmanship of this 30-year-old annual event for the display industry.

Hong Kong-born Tang has been recognised for the invention of the high-efficiency organic light-emitting diode (OLED), and is commonly known as the “Father of OLED”. He is the first Chinese to receive the prestigious Wolf Prize in Chemistry, awarded in 2011 for his discovery of OLED, which is starting to replace LCDs in smartphones, computers and televisions.  The Wolf Prize is considered second only to a Nobel Prize

Here are four ground-breaking projects currently in progress at the SKL.

1. Field sequential colour LCDs

While field sequential colour technology (in which the primary colour information is transmitted in successive images) is regarded as a more eco-friendly alternative colour filter for use in LCDs, it cannot be widely implemented owing to limitations in speed. The SKL has tackled this problem by reducing the display time from a few milliseconds to 0.01 milliseconds. This provides a radical increase in speed.

“This is a game-changing achievement, and we expect mobile phone and tablet manufactures to start applying field sequential colour LCDs in their products within the next two to three years. That will save a considerable amount of power, and make the world greener,” says Kwok.

2. Halving OLED TV production cost

In recent years, active-matrix organic light-emitting diodes (AMOLED), which offer a better display quality, have become a threat to the dominant position of LCDs. But AMOLED requires a component called low temperature poly-silicon (LTPS) thin film transistor (TFT) to achieve a high definition display.  The SKL turned the tide by creating a breakthrough technology called BG to replace LTPS at a 50 per cent lower cost.

“Hundreds of billions of yuan are currently spent in the mainland to build new LTPS and metal oxide production lines. So the application of BG technology will help China save a considerable amount of money, and make AMOLED displays more cost-effective,” says Kwok.

3. A new breed of e-papers

Recent years have seen a wider use of e-paper technology which enables a display screen to be rolled and folded like a sheet of paper.  The SKL has made dramatic advances in boosting e-paper display quality, and also made progress in the fight against counterfeiting.

According to Kwok, many countries have put a transparent coating on their bank notes using e-paper technology. In the past only rough black-and-white patterns could be stored on the coating. But the SKL has rolled out a new technology which allows a high-definition colour images to be stored. This will enhance the effectiveness of counterfeit detection.

4. Optimising LCD production with photoalignment

Rubbing alignment is an important process step in LCD manufacturing, but it limits the size and quality of the product. HKUST has recently developed a photoalignment-based technology which has a key advantage over rubbed alignment, as it allows the liquid crystal alignment direction to be freely patterned.  This results in better display quality, and the possibility of making larger and wider LCDs. 

Kwok says that research projects at the SKL will continue to concentrate on the following main areas: oxide thin film transistors (TFT) array technology; third-generation organic LED (OLED) devices; liquid crystal display (LCD) devices; video signal processing; integrated circuit (IC) design; and other frontier technologies.

The HKUST SKL is supported by a subsidy of the Innovation and Technology Commission of the Government of the Hong Kong Special Administrative Region.  It’s set apart from its competitors by the collective vision of Kwok, Tang and every dedicated researcher involved in creating a greener, safer future for the world.

Kwok says that the green display technologies being developed at HKUST can reduce the power consumption of electronic devices by between one-third and one-fifth. A mobile phone battery, for example, could last nine days after just a single charge. This day will come very soon, he says.