BACKGROUND: Materials scientists are developing camping tents that light up on the inside simply by plugging it into a battery. But there are no bulbs of any sort. The fabric itself emits light. Crosslink, a leader in electroactive polymer materials, is developing a crushable, durable, lightweight electroluminescent technology based on polythiophene, a plastic that conducts electricity. It can be made to emit either visible light or infrared light.
ADVANTAGES: The treated fabric panels serve two potential purposes. First, the panels can light the inside of the tent with visible light, replacing the need for traditional bulbs. Second, the technology can also give off infrared light, which is sensitive to heat and invisible to the human eye. The U.S. Army is interested in using the fabric for battlefield tents because soldiers could use their standard issue night vision goggles to read specially treated documents and maps without indicating their position to hostile forces. SuperFlex can also withstand being twisted, punctured, torn or scrunched-up without losing its ability to light up. The military could also use it, for instance, in a foldable map that emits its own infrared light so it can be read in complete darkness using night vision goggles.
ABOUT LEDS: LEDs are essentially tiny light bulbs that fit into an electrical circuit, but they are lit solely by the movement of electrons in a semiconducting material. A diode is the simplest semiconductor device. It is made by bonding a section of a positively-charged material to a section of a negatively-charged material with electrodes on each end so that it only conducts electricity (in the form of free-moving electrons) in one direction whenever a voltage is applied to the diode. Electrons move in a series of fixed orbits around the nuclei of atoms. Whenever an electron absorbs extra energy from the added voltage, it jumps to a higher orbital, and when it returns to a lower orbital, it emits the extra energy as a photon -- a particle of light. LEDs are specially constructed to emit a large number of photons, unlike ordinary diodes, in which the semiconductor material absorbs most of the light energy before it can be released. LEDs are also housed in a plastic bulb to concentrate the light in a particular direction. Polymer light-emitting diodes emit light when an electric current runs through them.
The Institute of Electrical and Electronics Engineers, Inc., and the Materials Research Society contributed to the information contained in the TV portion of this report.