CATHODE-RAY tubes relied on phosphors made of inorganic chemicals to generate their pictures. They, however, are history. Many of the flat screens that replaced them—whether liquid-crystal displays or more modern organic light-emitting diode displays—rely on organic chemicals instead. These tend to be less stable, and thus less long-lived than inorganics. A good, cheap way of making inorganic displays would thus be welcome. And one beckons in the form of systems that exploit a phenomenon called surface plasmonics to generate their colours.
The resonance of the surface electrons of tiny bits of some metals creates colour (a suspension of gold particles, for example, can be a pleasing shade of green). But attempts to use this phenomenon to create the full range of colours plasmonically, by producing the primaries—red, green and blue—have foundered. Gold yields vibrant reds and greens, but cannot manage blue. Silver can do all three, but is prone to oxidation and thus of limited practicality. And, in any case, these noble metals are expensive. But Jana Olson, of Rice University in Houston, Texas, and her colleagues think they have cracked the problem. In a paper just published in the Proceedings of the National Academy of Sciences, they describe how to do the job with aluminium.
