The explosion in computing and personal devices in recent years has led to a world where we are constantly surrounded by displays. Whether they belong to personal computers, laptops, smartphones, LCDs, PDAs, or MP3 players, there is no shortage to the amount of screens we can consult. In turn, this proliferation has led computer scientists and engineers to address a number of imperfections these displays have.
For instance, some of these displays don’t work in direct sunlight or are subject to glare. Others are horridly energy-inefficient and will drain their battery life very quickly. Some don’t have high-definition, rich color, and can’t display true black color. Just about all of them are rigid, and all can be broken given a solid enough impact. Luckily, a new age of flexible, ultra-HD screens are on the way that promise to resolve all of this.
The first examples of this concept were rolled out at the 2011 Consumer Electronics Show, where Samsung unveiled its revolutionary new AMOLED display on a number of devices. This was followed up in September of 2012 when Nokia unveiled its Kinetic Device at the World Nokia Conference in London. Both devices showcased displays that could bend and flex, and were followed by concept videos produced by electronic giants Sony, 3M and Microsoft.
Since that time, numerous strides have been taken to improve on the technology before it hits the open market. In research published earlier this month in Nature, scientists describe what may be the first steps toward creating a new type of ultrathin, superfast, low-power, high-resolution, flexible color screen. If successful, these displays could combine some of the best features of current display technologies.
The new displays work with familiar materials, including the metal alloy already used to store data on some CDs and DVDs. The key property of these materials is that they can exist in two states – when warmed by heat, light, or electricity, they switch from one state to the other. Scientists call them phase-change materials (PCMs); and as Alex Kolobov, a researcher at Japan’s Nanoelectronics Research Institute who was not involved in the new work, explains:
It is really fascinating that phase-change materials, now widely used in optical and nonvolatile electronic memory devices, found a potentially new application in display technology.
A PCM display would work similar to the electronic paper used in products like Amazon’s Kindle reader. Both are made by sandwiching a material that has two states, one lighter and one darker, in between layers of transparent conductors. The inner material is a viscous black oil filled with tiny white titanium balls. To make a pixel black or white, a current is run through a tiny area of the glass to either pull the reflective balls to the front, or cause them to recede.
In a PCM display, the inner material is a substance made of silicon’s heavier cousins: germanium, antimony, and tellurium. The two states of this material (known as GST) are actually two different phases of matter: one an ordered crystal and the other a disordered glass. To switch between them, current pulses are used to melt a tiny column, and either cooled gently to make the crystal or rapidly to make the glass.
This cycle can be done remarkably quickly, more than 1 million times per second. That speed could be a big advantage in consumer products. While scrolling on a Kindle can be terribly slow because the screen only refreshes once per second, the refresh rate on a PCM display would be fast enough to play movies, stream videos, and perform all the tasks people routinely do with their devices.
To make the new displays, the research team – led by Harish Bhaskaran, a nanoscale manufacturing expert from Oxford University – used a 35-year-old machine developed by the semiconductor industry. They then laid down three layers that were a few nanometers thick of conducting glass, GST, and another layer of conducting glass. Then they used current from the tip of an atomic force microscope to draw pictures on the surface.
These images included everything from a Japanese print of a tidal wave to fleas and antique cars – each one smaller than the width of a human hair. With this sort of flexible, ultra-high resolution screen, a PCM display could be made into everything from a bendable laptop and personal device to a programmable contact lens — like Apple’s Retina Display, except that it would actually fit on your retina.
Turning this technology into products will require years of labor and hundreds of millions of dollars. Nevertheless, Bhaskaran and his colleagues are optimistic. The electronics industry has lots of experience with all the components, so there are plenty of well-known tricks to try to improve this first draft. And they are hardly alone in their efforts to bring flexible displays to market.
For instance, LG unveiled their new line of flexible OLED TVs at CES earlier this year. Now, they are taking things a step further with the unveiling of two new 18-inch OLED panels, the first of which is a transparent display, while the second can be rolled up. Although both fall short of the 77-inch flexible TV on show at CES, the company says the new panels prove that it has the technology to bring rollable TVs with screens in excess of 50 inches to market in the future.
Unlike their 77-inch flexible TV that has a fairly limited range of changeable curvature, LG Display’s latest flexible OLED panel can be rolled up into a cylinder with a radius of 3 cm (1.18 in) without the function of the 1,200 x 810 pixel display being affected. This is made possible though the use of a high molecular substance-based polyimide film to create the backplane, rather than conventional plastic .
The transparent OLED panel, on the other hand, was created using LG Display’s transparent pixel design technology. With transmittance of 30 percent, the company says the panel is superior to existing transparent LCD panels that generally achieve around 10 to 15 percent transmittance. LG Display claims to have also reduced the haze of the panel, caused by circuit devices and film components, to just 2 percent.
As In-Byung Kang, Senior Vice President and Head of the R&D Center at LG Display, explained:
LG Display pioneered the OLED TV market and is now leading the next-generation applied OLED technology. We are confident that by 2017, we will successfully develop an Ultra HD flexible and transparent OLED panel of more than 60 inches, which will have transmittance of more than 40 percent and a curvature radius of 100R, thereby leading the future display market.
Granted, it will be still be a few years and several hundred million dollars before such displays become the norm for computers and all other devices. However, the progress that is being made is quite impressive and with all the electronics megagiants committed to making it happen, an age where computing and communications are truly portable and much more survivable is likely just around the corner.