Flat-packed technology - part 1
What do a pop group, a peer of the realm, a Japanese electronics company, a chemical manufacturer and a
bunch of Cambridge scientists have in common? Answer: they are
all involved in a technology company that will soon bring us the
world's first full-colour plastic TV screen.
The story began in the 1970s when polymer scientists discovered that some polymers could surprisingly carry a current. The possibilities of plastic wires and lightweight circuitry were obvious although not immediately practical but one additional effect was that a small few of these materials when specially prepared could glow weakly in ultraviolet light or when carrying a current. The idea of using them in displays began to emerge. At this time, however, liquid crystal displays were becoming fashionable with manufacturers of the new digital watches and calculators, and were displacing inorganic light-emitting diodes providing the cash to develop LCDs to the point at which they would be fast and slick enough for computer technology. Countless laptop computers around the world now use LCD displays.
The trouble with LCDs though is that they although liquid crystals are now rather well understood actually incorporating them into devices is still a rather complicated process so they are expensive to manufacture and control. The construction of displays, is awkward, requiring careful sandwiching between two layers of transparent materials one of which has to be a perfectly aligned polarising layer. Once assembled, LCDs are fragile, can often only be viewed within a very narrow angle and then only in perfect ambient light. Many technologists feel that an easier to make and more robust alternative system could usurp LCDs. Which is where the glowing plastics come in.
The conducting polymers studied in the 1970s and 1980s were simple affairs. Simply a strand of carbons linked by conjugated double bonds. Appearances are often deceptive though. The conjugation can endow the polymer with excitable electrons give them a kick with UV or an electric current and they become agitated, leaping to higher energy levels, when they drop back down photons are ejected. If these photons have the right wavelength we see a glow. This remarkable property was not lost on bright sparks at the Cavendish Laboratory in Cambridge. Physicists Jeremy Burroughes, Donal Bradley and Richard Friend figured that electroluminescent polymers might be used to make tiny light-producing electronic components. The fact that they would be plastic might make them less fragile than inorganic semiconductor materials chipped off synthetic crystals. These devices would be much lighter and could even be bent they would be so tough. The idea of packing such devices into an array with a means to control their glow electronically would produce a simple display that could effectively be any shape or size you like, from pocket TV to 360-degree cinematic surround screen, from lightweight and comfortable virtual reality headsets to huge video advertising hoardings in Piccadilly Circus. The commercial implications were enormous...