A light-emitting diode (LED) is an efficient electrical means of creating light. Using a semiconductor circuit called a diode, an LED produces light in a variety of colors, depending on the materials used in its manufacture. LEDs are more compact, reliable, and longer lasting than traditional light bulbs and use a fraction of the energy. First used in the 1970s, LEDs became increasingly popular and ubiquitous in the 21st century. The light-emitting diode may eventually replace the light bulb as developing technology makes it cheaper and more efficient.
LEDs work on the property called electroluminescence, in which some materials generate light when charged with an electric current. The effect was first documented in 1907, and LED technology was pioneered by the Russian scientist Oleg Losev two decades later. The high cost of materials meant that practical applications for the light-emitting diode were not developed until the 1960s. By the 1970s, the small red lights were used in small devices such as watches and calculators and as power indicators for larger appliances. Advances in semiconductor technology gave LEDs wider variety and applications at the dawn of the 21st century.
A diode is a circuit that controls the flow of electricity using a semiconducting material such as silicon. A light-emitting diode uses this property to manipulate electrons into creating light. This process is more energy efficient than standard light bulbs, meaning little electricity is wasted, and the diode can last far longer than a bulb. The first LEDs had a limited color range, chiefly red, blue, and yellow. Advances in technology have increased the brightness of LEDs and given them colors across the spectrum.
LED lights are more expensive to produce than incandescent or fluorescent light bulbs, but their long lives make them ideal for locations where replacing bulbs is difficult. They are often used as internal and external lighting for cars, boats, and aircraft. Many traffic signals, street lights, and signs also employ some form of a light-emitting diode array. LEDs provide backlight to illuminate the screens of laptops, phones, and mobile devices. By the early 2010s, they had taken on a wide range of decorative and practical lighting uses.
The light-emitting diode does have some disadvantages. At high power levels, it has been prone to losing efficiency, a property electrical engineers call droop. It can be sensitive to changes in temperature, voltage, and current level. Creation of white LED lights was delayed for many years because of the limitations of the LED spectrum, a property of the semiconductor materials. As these limitations are overcome by advancing technology, LED technology is expected to become increasingly widespread around the world.
