22 September – From The Economist – With many countries phasing out the use of traditional incandescent light bulbs to save energy, the lighting business has taken on a new dimension and is now offering a broader range of products than the one perfected in 1879 by Thomas Edison. There are compact fluorescent lights (CFLs), light-emitting diodes (LEDs) and some firms are developing quantum dots, which are lights made from tiny crystals of semiconducting material. Now another new source of lighting, organic light-emitting diodes (OLEDs), is starting to take the spotlight.

Philips, which is based in the Netherlands, has produced a strip of lighting made from OLEDs that can be powered directly from a mains electricity supply. That may not seem to be a brilliant invention, but in the lighting business it is a breakthrough. Although still at the laboratory stage, it will eventually mean that bulky power electronics and transformers will no longer have to be used with OLED lights, which brings down costs, simplifies design and allows them to be fitted into more products. In recent years the emergence of mains-powered CFLs and LEDs has started to turn them into direct plug-in replacements for incandescent bulbs. OLEDs, however, will fulfil a different role.

Compared to an incandescent bulb, which might cost only about 50 cents and burn for 1,000 hours, CFLs cost around $3—although they use up to 75% less power and last much longer. LED lights cost a lot more, but they are even more efficient. Osram, which is part of Germany’s Siemens, recently launched the Parathom Classic, a LED lamp shaped like conventional 60 Watt light bulb. It uses 90% less power than an old-type bulb and has an average life of 25,000 hours. It has gone on sale in Europe for around €50 ($64).

The quality of light from these new bulbs is different. Some people prefer the warmer glow of an incandescent bulb to the light produced by CFLs. Nor do they like the time it takes for these bulbs to reach their maximum illumination. Unlike an incandescent bulb, which uses electricity to heat up a wire filament sitting in a low pressure inert gas encased in glass, a CFL uses electricity to excite mercury vapour, which produces an ultraviolet light that causes a phosphor coating on the inside of the bulb to glow. Disposing of the mercury once these bulbs wear out causes some environmental concern.

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