Light emitting diode, generally known as LED has become one of the essential electronic components in our daily life. LEDs are everywhere! From traffic lamp to reading light, from vehicles to remote! Actually, we are surrounded by LEDs. So, why LEDs have become so much popular! There are of course some great reasons. To describe LED, first, we should take a look at the history of electrical light. We know the first commercially light was invented by Thomas Alva Edison in 1878. He tried almost everything for a perfect filament and succeeded by using tungsten. Although it was a very important invention, in the case of efficiency, it was not so good. The tungsten bulbs convert only 5% of their total given energy to light, in case of practical use, it remains mostly at 2.2%, most of the given energy is converted to heat. So, to work on the problem, scientists pay attention to invent efficient light bulbs. To fulfill this objective, the researched and invent Fluorescent bulbs. Although fluorescent bulbs were more efficient than tungsten bulbs and did not produce too much heat and were also capable of working in low energy, its efficiency was not also more than 10%. So, scientists further look forward to inventing a more efficient light source. In the middle of the nineteen century, a German scientist named Ferdinand Braun invented the first semiconductor diode. As we are talking about light emitting diodes, so we have to go through the diode first. So, after the invention of the diode, there comes

a revolution in the field of electronic and science. Soon after the invention of the diode, the legendary transistor was invented by joining two back to back diodes. The invention of the transistor was really a milestone in the field of science. Later it was followed by JFET & MOSFETS. So, we were talking about LEDs. So, after doing so much research and collaboration on diode, the first LED was invented in 1961 by James R. Biard & Gary E. Pittman and commonly was used in various remote control & other devices cause it was an infrared LED. So there was still no scope of visible light. Being inspired by the infrared LEDs an American Engineer Nick Holonyak first successfully invented an LED emitting visible light in 1962. It was a shiny bright semiconductor diode emitting Red light! Later it was followed by George Crawford and Shuji Nakamura by inventing yellow & blue light gradually in 1972 & 1993. Though various kinds of visible lights were invented, still white light was a quest for scientists. As we know, blue LED was invented late (in 1993), before that, it was not possible to make white light because as we know the white light is a complex light and is a mixture of various colors. It was really a tough challenge for the scientists to make white light as blue LEDs were yet to invent. Creating a blue LED was a difficult challenge, after researching for several years, the Japanese Engineer Shuji Nakamura invented a bright blue LED by using gallium nitrate. So, after this long path, we are now belonging in the era of LED. Can we imagine that the tungsten light bulbs which consumed average 30 watts were replaced by a component which consumes only 2.5 watts on average! Really it was a

miracle. LEDs are replacing almost every light sources around us and it would not? LEDs are cheap, LEDs consume less power, LEDs are more efficient. Various kinds of LEDs are now being used for various purposes. In medical science, space science security and everywhere! Now we click photo by using LED flash and also see them in the LED monitor screen. Doctors use LED enabled sensors to find diseases. Police are using LED lights to keep documents of the criminals. Optical mark readers are being used hugely to count marks and give results. Not only that, fingerprint sensors, smoke sensors and almost every kind of optical devices have been and replaced and the process is going. So, we cannot imagine a life without LEDs now. In street light, in rooms, in decoration everywhere is LEDs. Let me finish by a quote from the 2014 Noble Prize committee, “Incandescent light bulbs lit the 20th century, the 21st century will be lit by LED bulbs”. So, the next time you switch on your room lamp, try to recount the awesome contribution of different scientists who gave their time and knowledge to provide you with this great facility.

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