History of LED Light

The light-emitting diode (LED) is currently the most energy-efficient lighting technology available for use in commercial and business applications, and it is only natural that it is also one of the fastest developing technologies. The LED is a type of solid-state lighting in which a semiconductor converts electricity into light (without generating heat), typically in a small area of about 1 square millimetre or less (the diode). So there are several light-emitting diodes in an LED lamp. The light produced is projected in one direction, eliminating the need for diffusers and reflectors.

The Development of the Concept of Electroluminescence

The idea of electroluminescence is at the heart of the development of LED luminaires. However, the emitted yellow light was too weak to be useful. At that time, this phenomenon was not further researched.

But again, the light emitted by this material was too weak to be of any practical use. The research on this phenomenon was stopped yet. The term "electroluminescence." was coined by George Destriau in 1936 when he published a report on the event that light is generated by zinc sulfide powder when an electric current is passed through the dust.

The First Light-Emitting Diode with Practical Application

In 1961, Robert Biard and Gary Pittman invented an infrared LED while working for Texas Instruments. However, this light had no possible use, as it was invisible to humans. This was a coincidental invention because Biard and Pittman were working on a laser diode.

Experiments with the semiconductor gallium arsenide, begun in the 1950s, later led to the development of the very first LED with practical uses. He designed these red diodes while working for General Electric. Holonyak has earned the title "Father of the Light-Emitting Diode".

Experiments with the semiconductor type that could produce more efficient LEDs continued in the 1960s. In the early years of this decade, LEDs were provided with gallium arsenide phosphide on a gallium arsenide substrate. Soon after, the production of orange LEDs began.

In 1972, M. George Crawford of the Monsanto Company used two gallium phosphide chips - one red and one green - to produce LEDs that emitted a bright yellow light. Incidentally, the Monsanto Company is the first company to produce LED lights on a large scale and for mass consumption. Crawford also invented an LED that emitted light about ten times brighter than the Holonyak version.

In the mid-1970s, scientists began to use only gallium phosphide to produce LEDs that emitted a pale green light.

The use of LED lights became popular during this decade as Fairchild Optoelectronics began to manufacture low-cost devices.

The First Generation of Super-bright LEDs

Continuous and intensive research and development work in LED technology led to the development of the the first generation of super bright red, yellow and green LEDs in the early 1980s. In the early 1990s, scientists experimented with indium-gallium-aluminium phosphide as a semiconductor material to produce ultra-bright orange-red, orange, green and yellow LEDs.

In 1994, Shuji Nakamura invented the ultra-bright blue LEDs made of gallium nitride, and soon after, high-intensity blue and green LEDs made of indium gallium nitride were developed. These ultra-bright blue LEDs formed the basis for the development of cost-effective and highly functional white LED lighting fixtures that are now commonly installed in commercial and production facilities, as shown in the figure below. The scientists discovered that by coating the blue light-emitting chip with fluorescent phosphors, the diode could be made to emit bright white light.

The results produced by the white LEDs were impressive, and the U.S. Department of Energy promoted the development of white LED technology, taking into account the needs of business owners to illuminate their premises with cost-effective solutions.