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Endesa - Electricity, Gas, People

The true origin of LED bulbs

Published on November 26, 2019

LED lights have become an indispensable element, both inside the home and in city lighting. Their long duration and low consumption have guaranteed their victory over other options. Behind this success, there is not one but several geniuses.

Presenting a convincing argument usually opens many doors. For example: LED lights last about 50,000 hours before failing. That equates to about 5 years switched on constantly.

Behind this invention is the work of many researchers and a story of genius and inventiveness that began with the idea for the original Humphry Davy bulb.

The first LED did not appear until 1962, when Nick Holonyak successfully completed a project that took many experiments and hours in the laboratory to get right. Below we will tell you the story of LED lights from their origin to the present day.

The forgotten work of H.J. Round

Many inventors have contributed to making it possible for us to have light today, but one inventor who is rarely talked about is Henry Joseph Round, an English electronic engineer who was the first person to come up with the theory behind LED lights.

Born in 1881, he is best known for his contribution to the development of radio communications and his work for the British Navy. In fact, his work was decisive in the victory during the naval battle of Jutland in 1916, in the First World War, as his radio system alerted English ships to the departure of the German fleet.

His contribution to LED development, although largely unrecognised, is still important. In 1907, while working on a radiogoniometry system for maritime transport, he discovered that inorganic materials can give off light. The publication of this finding in Electrical World magazine was the basis of many future studies.

H.J. Round had the initial idea: to illuminate inorganic materials.

The fathers of electroluminescence

It is no accident that another of the great minds that helped to develop radio also helped develop LED lights, since these technologies go hand-in-hand. Russian Oleg Lossew was the first scientist to demonstrate that a semiconductor crystal can generate and amplify radio signals. He also observed that the diodes used in the receivers emitted light when electric current was passed through them. His works between 1925 and 1941 resulted in a scientific patent for a light relay.

At the same time, French physicist Georges Destriau discovered that zinc sulphide can emit light. Although he is considered the father of electroluminescence by many, he was perfectly aware that his achievements were largely due to the work carried out by his Russian counterpart. That's why he called his invention the "Losev's Light".

From theory to practice

The discoveries of Henry Joseph Round, Oleg Losev and Georges Destriau created the theoretical framework for the next breakthrough that was made following the invention of the transistor. Thanks to this scientific milestone, which allowed the creation of the semiconductor industry, the necessary practical step was taken for the creation of the first LED.

This happened in 1962 at the hands of Nick Holonyak, an electrical engineer at General Electric. Holonyak created the first two-terminal electronic component that allowed electric current to circulate through it without needing a gas to be present. The Holonyak diode had a terminal through which the positive charge entered and another through which the negative one entered. Both were separated by a small space where there is a transition that produces light. This first diode used an alloy called GaAsP that resulted in a red light. The first LED had arrived. Its practical application was not yet important, but it led to hundreds of researchers turning to this new technology.

To improve it, he worked on other semiconductor materials that gave off green, yellow and orange light. Their brightness also improved over time. But it was not until 1995 that the first LED was introduced. It was released onto the market in 1997.

The first LED light was white and was released in 1997.

The future: green LED lights

Since then, the development of LED lights has been unstoppable and now anyone can buy them in any colour and with any level of brightness. They can be used anywhere from decorative lights and in the home to cars, televisions and street lighting.

They consume less, and last longer... and this is just the beginning. LED technology is already here and new developments are focused on the use of organic light emitting diodes (OLED) to achieve greater efficiency and be more environmentally friendly.

From LED we have moved to OLED lights, which are more efficient and environmentally friendly.