26 August 2013

New plastic light bulbs are cheap, bright, shatterproof, and flicker-free

A team of material scientists from Wake Forest University in North Carolina have developed plastic light bulbs that are shatterproof, flicker-free, and seem to last forever. Furthermore, these plastic bulbs are about twice as efficient as fluorescent bulbs, on-par with LED bulbs, and — perhaps best of all — they produce a color and quality of light that “can match the solar spectrum perfectly.”

These new bulbs are based on field-induced polymer electroluminescent (FIPEL) technology, with a twist. FIPEL is a fairly old technology that involves running electricity through a conductive polymer called poly(vinylcarbazole) to produce light — but not enough light to be used as a light bulb. Now, by doping the polymer with carbon nanotubes, Wake Forest has increased the polymer’s luminance by about five times — and voila, we’re into light bulb territory.

The new device, invented by David Carroll of Wake Forest, consists of three layers of polymer/nanotube material with dielectric layers sandwiched in between. When electricity is applied, electrons excite the electroluminiscent polymer to emit light — and the carbon nanotube doping seems to increase the amount of light emitted. Doping is very common in the field of electronics, where impurities are often added to silicon (or other materials) to change or enhance their electrical properties. The fundamental building blocks of transistors — p- and n-type silicon — are produced by doping with phosphorous, arsenic, boron, and gallium.

As far as longevity goes, Carroll says he has a FIPEL in his office that has worked for a decade. The most likely reason for such incredible immutability is because FIPEL produces only negligible amounts of heat — almost all of the electrical energy is converted into light. Without heat as a continual stressor, the polymer will probably remain stable for years.

Carroll says the plastic bulbs are cheap to make, and contain no mercury or other caustic materials. As we mentioned earlier, too, the quality of the light produced by Carroll’s FIPEL bulb is also very desirable, matching the solar spectrum perfectly (i.e. it’s not too yellow or blue). A “corporate partner” is already on board, and Carroll says that his plastic bulbs could be available as soon as 2013.

Now read: Light stopped completely for a minute inside a crystal: The basis of quantum memory

Research paper: http://dx.doi.org/10.1016/j.orgel.2012.10.017 – “Effect of multi-walled carbon nanotubes on electron injection and charge generation in AC field-induced polymer electroluminescence”


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