According to the website eere.energy.gov, LEDs consist of two electrodes (an anode and a cathode), a whisker, an anvil, a semiconductor and a lens, all contained within an epoxy resin. Power enters LED bulb systems through the anode. Electrical current then runs through the whisker, then the semiconductor and anvil. The current exits through the cathode. The epoxy housing focuses light produced by the bulb and protects the inside components from the outside elements. Color is determined by the chemical make-up of the bulb's semiconductor.
Light-emitting diodes are the smallest form of light bulb on the market. Each LED is constructed to a diameter of around 1/4 inch. The size has severely restricted LEDs' practical applications to instrument and electrical panels until recently. LED technology has evolved and increased its presence in the lighting industry with the development of "clustering." These light bulbs are clustered into groups of any number of LEDs, broadening their applications.
Properly manufactured LEDs can last for well over 45,000 hours, according to eere.energy.gov. All components of an LED are securely fastened into a solid epoxy shell. This makes the bulb very durable and able to withstand a certain level of jarring without breaking. Most types of light bulbs utilize delicate filaments in their construction; LEDs, however, require no filament, which adds to their durability.
Often when LEDs are clustered to form a light bulb that fits typical incandescent bulb sockets, they feature diffuser lenses. Diffusers are also used in LEDs for track lighting and flashlights because the lenses broaden the beams of light emitted by the light bulb. Part of the reason that LEDs last for so long is that they do not operate at high temperatures, according to the website eartheasy.com.
LED technology is linked with a very high cost of production, which is directly reflected in the average price of LEDs. One of the reasons for high production costs is that LEDs currently use sapphire-based technology in the construction of every LED. Silicon wafer-based technology is being researched at Purdue University. Replacing costly sapphire-based technology with silicon wafer-based technology promises to make LEDs much more affordable. The website treehugger.com notes that clustered LED bulbs that fit into everyday sockets are available for $60 and up.