LC Today: Industry & Applications News

More change in Japanese LCD industry

Panasonic will end production of liquid crystal display (LCD) panels used in televisions [1]. Their manufacturing plant, in Hyogo Prefecture, will end production by the end of September. The plant will still operate, but with a reduction in output of almost 75%. Panasonic will continue to produce televisions, but the liquid crystal (LC) panels themselves will be bought in from a third party.

This move comes at a time of upheaval in the Japanese LCD industry, where the price of LCD panels has fallen as a result of cheaper manufacturing in China and South Korea, and the onset of other technologies. The takeover of Sharp by Taiwanese electronics giant, Foxconn, was recently completed for approximately $3.5 billion, half the cost of the original bid, in a move which Sharp believe will greatly benefit their display business [2]. Consumers will likely not be affected by these changes, but the LC manufacturing industry is certainly becoming less diversified in the Asian region.

DNA alignment layers

LC molecules must be aligned for their use in display panels. The current industry standard is to use a polyimide alignment layer, which can have a high energy cost to the manufacturing process. Now, a group from the Korea Advanced Institute of Science and Technology (KAIST), situated in Daejeon, has developed a new alignment technique, using one of the most commonly found molecules on the planet: deoxyribonucleic acid, commonly known as DNA [3].

The structure of DNA is well understood, and the helical structure that it forms can be utilised as a template for the alignment of molecules such as LC. Not only is DNA a very cheap material to produce, due to its abundance in nature, but the alignment procedure can be performed at room temperature – an improvement over polyimide – which could potentially reduce the energy requirements for manufacturing.

The research group from KAIST, led by Dong Ki Yoon, applied an aqueous solution of DNA to indium tin oxide–coated glass – the standard transparent conductor used in displays. The solution was brushed in order to align the molecules, and the excess water evaporated. This layer was then successfully used to align LC molecules and produce a working in-plane switched LCD cell, with the final cell displaying optical qualities comparable to traditional techniques [4,5].

New LC materials for extreme temperatures

Materials which allow LCDs to operate at extreme temperatures have always been sought after, especially with the recent prevalence of LCDs in cars or other locations exposed to the environment. Indeed, many consumers are becoming more aware of the finite operating range of LCDs as weather experienced across the world becomes more extreme. Now, a research group at the University of Central Florida, led by Dr Shin-Tson Wu, has developed a new LC material which can operate at greater temperature range than those currently in use for displays [6].

The current operating temperature range for a car LCD is −30–85°C. However, European standards dictate that the response time should be <200 and <300 ms at temperatures of −20°C and −30°C, respectively. At these response times, the display would be noticeably blurry during operation. The new work by Dr Wu’s group of doctoral students, including lead author, Fenglin Peng, reports several materials with a wide nematic range of −40–100°C [7].

The new materials are reported to operate at <1 ms grey-to-grey (GTG) at >35°C. More importantly, a GTG response time of <10 ms is reported with their new material while operated in a fringe field switched mode at 0°C, and a twisted nematic mode at −20°C. The material still has room for improvement: the response at temperatures under −20°C is still in tens of milliseconds; however, this is almost an order of magnitude improvement over other commonly used materials.

Cambridge smart windows

A research group at the Centre for Advanced Photonics and Electronics, at the University of Cambridge, has developed a new smart window technology based around Smectic A LCs [8]. The researchers, in collaboration with Dow Corning, have developed a glass-based LC composite which can be electrically switched between transparent and opaque. Not only has the new glass proven its endurance under millions of switches, but it is capable of easily varying the opacity, leading to a material that could be adjusted based on sunlight.

Smart window technology is quite sought after at present, not only when privacy might be required but with the prevalence of large glass-based skyscrapers, it is seen as a necessary technology to regulate the temperature of the building. The initial materials were all glass-based; however, they have also reported the ability to utilise roll-to-roll processing in order to print large areas onto plastic.

Another promising aspect of this technology is the switching time that the group has reported. While large smart window panels will often only be capable of switching on timescales of seconds, these devices have switching reported on much faster scales of a few tens of milliseconds [9].