As microprocessors, hard drives and memory chips have raced along over the past decade, the means to display their data has crept slowly forward. That may be about to change, thanks to the biggest breakthrough in the visual display of words and pictures since the invention of television–a new technology that promises a world where information is portable, cheap and stunningly vivid. Just around the corner are roll-up screens that tuck into a pocket. A weapons inspector in Iraq could unfurl a map of his surroundings, fed with color-coded hints of nasty stashes and real-time satellite images. Stateside, such displays will make it easy to surf the Web or watch TV any place, any time, without having to lug a laptop.
The secret lies in harnessing organic polymers to function as pixels. And like many important discoveries, this one was born of a happy accident. In 1989, tinkering with materials he hoped would amplify electrical signals, Cambridge University physics professor
Before he could crack that one, Friend was fixing on potential implications. Organic polymers are a fundamentally new way of converting electricity to light, a process at the heart of all displays–TVs, computer monitors, cell phone screens.
The last century has seen only a few major display innovations, among them the move from black-and-white monitors to color and the introduction of flat, liquid crystal displays to replace cathode ray tubes. If Friend’s discovery lives up to its promise, the LCD will someday be tossed aside in favor of the OLED–organic light-emitting display.
While LCD screens have made major strides, they have two inherent problems: They gulp energy and are extremely brittle. A standard computer screen is the single largest drain on power–and the main reason laptops poop out after three hours of use. Today’s LCDs are backlit; they work by filtering out different colors to produce a picture. By contrast, each point on an OLED screen can be fed electricity individually, so dark pixels waste no energy; each pixel also gives off more light than an LCD–with the same amount of electricity. OLED screens could extend the life of a laptop battery to ten hours, says
Since OLEDs don’t need to be sandwiched between glass, they can be sprayed onto a wide variety of flexible surfaces, making them durable, flexible and cheap. That allows for roll-up screens; they could even one day be built into wallpaper or clothing.
In 1989, when Friend made his initial discovery, such talk seemed the stuff of cheesy sci-fi. “There was a whole community of doubters looking at their textbooks for inspiration, or perhaps I should say for lack of inspiration, and saying it couldn’t be done,” says Friend. “The science has been an astonishing story of the unexpected followed by the unexpected, and the unexpected has almost always turned out to be good news.”
Example: The principles of standard quantum mechanics suggested that OLED screens could never be super energy-efficient. Only a quarter of the energy could ever be turned into light, the theory went; the other 75% would go to waste. With a little experimentation (and rethinking of basic physics), Friend discovered that the theoretical barrier was an illusion.
While Friend fought conventional wisdom in the lab, he waged a similar battle at Cambridge. In 1992 he convinced Cambridge to turn his breakthrough into its first-ever spinoff–to be known as
Still, the commercialization made this lifelong academic extremely nervous. “I wasn’t sure that it was going to be a good thing for my career,” he says. He needn’t have worried. His original 1990 paper on glowing organic polymers, published in Nature, became Friend’s most widely cited research, according to Science Watch, which tracks academic research. In 1995 Cambridge appointed him to the prestigious Cavendish professorship, whose list of past incumbents includes James Maxwell (1831-79), who created the theory of electromagnetic waves.
Friend still faces challenges. A year before his discovery two U.S. scientists at Kodak made a similar finding. But their technology was based on the luminescent abilities of small organic molecules–single molecules–in contrast to the large ones–chains of molecules–Friend utilized.
There’s a substantial difference. Small organic molecules won’t dissolve in a liquid and so must be deposited onto a screen using a process similar to etching a standard computer chip. But because the screens are much larger than chips, that gets expensive. Friend’s large molecules can be mixed into a solution and sprayed onto a screen, using the same technology as ink-jet printers. That potentially offers vastly lower production costs.
Kodak’s small-molecule OLEDs, which make better use of current manufacturing technology, proved quicker to develop. The company is currently shipping 2.2-inch OLED screens, featuring bright colors and wider viewing angles, to partners who will be announcing products–likely handheld devices–in the first quarter of 2003. Cambridge Display dominates the large-molecule segment, having just acquired its main rival, a British firm called Opsys. It has licensed its technology to DuPont, Philips and Seiko-Epson.
Even more exciting, large organic molecules can be exploited in a reverse process–converting light to electricity–with potentially far-reaching effects. Solar panels that heat pools or power handheld calculators rely on silicon semiconductors to turn light into electrons. How much more efficiently could they be run if Friend’s organic polymers replaced silicon? That’s an open question. Many of Friend’s papers have explored just that possibility. At the moment, organic molecules can’t yet beat silicon in photovoltaics. But Friend envisions a time when the casing of a handheld computer or telephone will have one organic polymer that soaks up a room’s light and uses it to juice a battery, which then powers one of his hyperefficient OLED screens.
Friend is casting his mind out even further. OLED could open new areas of art or, more prosaically, lead to a new kind of camouflage bodysuits, even constantly updated newspapers that look and feel like the original thing. “One always falls into the trap of going into the straight-replacement mode,” he says. “But with a revolutionary technology you should not simply map it on to existing products. Not if you are an optimist.”