You know times have changed when they light up the Sistine Chapel.
For nearly 500 years, Michelangelo’s timeless masterpiece was lit only by scattered sunlight filtering through the chapel’s small windows. Unfortunately, the ultraviolet rays were beginning to deteriorate the colors. Adding incandescent bulbs into the mix would have only made things worse, but a new kind of illumination is ready to bathe the Sistine Chapel in a glow Michelangelo could have never imagined. In 2014, the chapel was fitted with 7,000 light-emitting diodes, or LEDs for short.
If this is a sign that we’re moving into a new age of artificial light, it’s not the first one. In 2007, the U.S. Congress ordered the gradual elimination of inefficient, incandescent light bulbs off the market. As of January 1st, 2014, the most popular wattages of the bulbs were no longer sold in stores. After more than a hundred years of use, the United States – and much of the world – said goodbye to lighting technology that was holding us back.
There are still some incandescent light bulbs on the shelves, but they aren’t being manufactured like they used to be. Though the immediate replacements have been compact fluorescent bulbs, experts in the lighting industry think LEDs are the wave of the future. Even today, this emergent technology can be found in clocks, watches, Blu-Ray players, Christmas lights, computers, TVs, and more.
As ubiquitous as they suddenly are, the road to mainstream prominence was a long one.
Did You Know? – Energy & LEDs
As important as incandescent bulbs have been to modern society, they are terribly wasteful. Almost 90 percent of energy is produced as heat rather than light. CFLs (“Contact Flourescent Lamps”) aren’t much better, releasing approximately 80 percent of energy as heat. LEDs are more efficient, using up to 75 percent less energy than incandescents.
Part I – History of the LED
Like every scientific discovery, the development of light-emitting diodes happened over time, gaining progress in fits and starts. Early pioneers like H.J. Round, Oleg Losev, and Rubin Braunstein laid the foundation in the first half of the 20th century, experimenting with crystals and gallium arsenide to produce the first examples of electroluminescence. When it came to finding practical uses for their breakthroughs, however, the field was left wanting.
That started to change in the fall of 1961 when a couple of Texas Instruments researchers discovered that gallium arsenide emitted infrared light when exposed to an electrical current. James R. Biard and Gary Pittman earned their place in history as the fathers of LED light when TI introduced the SNX-100 the following year. The first example of an infrared LED bulb, the SNX-100 produced a 900 nanometer wavelength of invisible light and used a pure GaAs crystal as its sole source of illumination.
The next decades saw LEDs move beyond their humble beginnings. One of the most important advances, however, took place almost simultaneously. In 1962, Nick Holonyak, Jr. of General Electric developed the first visible-spectrum LED. Holonyak’s red LED was later followed by yellow light in 1972, invented by M. George Craford, a former student of Holonyak’s. Low light output from these LEDs limited their usefulness to anything more than indicators. For LEDs to become a legitimate source of light, researchers would have to figure out how to boost their output.
In the 1990s, Isamu Akasaki, Hiroshi Amano, and Shuji Nakamura did just that. With breakthrough development that earned the trio the Nobel Prize in 2014, they invented the first blue light beams, creating a revolutionary step forward in commercial lighting technology. With the blue LED, bright white light was now a possibility. More energy efficient and environmentally responsible than incandescent bulbs, the new LED lights could move worldwide power consumption into a brave new age.
Is That So? – A Short LED Fact
In 2009, the Guinness Book of World Records recognized Mitsubishi’s scoreboard at Cowboys Stadium as the World’s Largest HD Video Display. The board is comprised of four LED video screens, two of which are 72 feet high and 160 feet wide.
Part II – How the LED Works
LEDs aren’t just the updated version of Edison’s incandescent light bulb. LEDs get their light through electroluminescence, a phenomenon wherein a material emanates light when an electrical current is passed through it. For the purpose of LEDs, a semiconductor material is used. Germanium and silicon are among the most common of these materials. To prepare them for use, scientists “dope” the materials with other elements in order to create electron holes.
What are electron holes? These are pockets in atoms that have no electrons, meaning they hold a positive charge. When scientists change the structure of these atoms, filling in the electron holes, they can create two different semiconductor types within the same crystal. Between the two lies a boundary known as a p-n junction. This boundary only allows current to pass in one direction, making it the perfect diode. Electrons are sent from one crystal to the other, filling electron holes, and producing the electroluminescence that makes the LED what it is.
One of the first challenges engineers faced when developing LED technology was figuring out how to control the output. The typical “light cone” coming out of the semiconductor is extraordinarily narrow, a problem solved by making the light bounce off every surface of the crystal. Once researchers were able to harness the power of that refraction, they could achieve a more intense output appropriate for commercial use.
Finally, there was the matter of creating white light. As we’ve noted, this was accomplished by first developing a bright blue LED. Once Akasaki, Amano, and Nakamura were able to do that, everything changed. From their humble, indicator-light origins, LEDs were now able to be used in everything from table lamps to traffic signals to cellphone flashlights.
But while the future may be wide open when it comes to LED applications, it would be unfortunate to forget what an important role these lights played in a technology very near and dear to our hearts.
Ho, Ho…Oh! – LEDs & Christmas
While our traditional incandescent Christmas light bulbs may only have about 1,800 hours of use in them, LED Christmas lights can still brighten your tree after 4,000 hours.
Part III – LEDs In Clocks and Watches
When Stanley Kubrick’s 2001: A Space Odyssey debuted in 1968, critics and fans alike found themselves agape at this transformational view of the future. Though the extraordinary themes and heart-pounding special effects were central to the film’s success, Kubrick knew that the devil was in the details. To that end, he wanted to put new technology everywhere. He met that goal, in part, by making a deal with the Hamilton Watch Company. In search of a clock display that looked like nothing anyone had seen before, Kubrick commissioned Hamilton to provide him with a futuristic digital display.
While the glowing red numbers on the clock worked for the movie, they also inspired the company to make something similar for the real world. Only a couple of years later, the world’s first “wrist computer” made its debut on the national stage. Retailing for an astounding $2,100, the Pulsar was hardly a smash mainstream success. Still, the LEDs used to provide a digital display element would soon change the way the world checked the time.
The early digital watches used seven electronic switches in creating the glowing numerals. A semiconductor called aluminum gallium arsenide was used the emit the red light, though clockmakers soon added green LEDs into the mix by using gallium nitride. Because the LEDs used so much power, users had to press a button each time they wanted to see the time. It wasn’t until costs came down and battery power was reduced that Texas Instruments was able to market LED watches and clocks for less than $20.
The Pulsar may not have been on every American wrist, but its legacy lives on through the 21st century. In its day, it became a symbol of the future and a hallmark of discerning luxury. President Gerald Ford was among its many admirers. Much later, Time Magazine named it one of the top twenty watches of the 20th century. Today, this remarkable example of LED technology and forward-thinking progress enjoys a well-deserved home in Washington D.C.’s Smithsonian Institution.
New Look For An Old Icon – LEDs and New Year’s Eve
To mark the hundredth anniversary of the Times Square New Year’s Eve Ball, the old halogen bulbs were ousted in favor of 9,576 LED bulbs capable of producing more than 200 colors.
Part IV – The Future of LEDs
We’re only starting to see how LEDs are changing the way the world is lit. As costs come down, experts predict we’ll start seeing LEDs used everywhere we currently see CFLs and incandescent lighting. With their improved brightness, reduced energy usage, and better lifespans, LED lights are winning over consumers in both the commercial and private sectors.
Right now, LEDs account for about 20 percent of the lighting market, but industry observers believe that number could grow to as much as 70 percent by 2020. Already, we’ve seen Los Angeles replace their famous arc-sodium streetlamps with bright white LED lights, taking the city out of the orange haze its been engulfed in for decades. Other cities, including Austin, Las Vegas, and San Antonio have followed their lead.
A cousin to LEDs, the organic light-emitting diode (OLED) is also making a splash on the lighting market. Researchers have begun to use OLED technology to create entire sheets of light, meaning we could be only a few years away from walls and ceilings that act as their own light source. Already, this technology has been used to make some of the most stunning televisions in the field.
Then there is the laser, which some scientists think will provide us with illumination long after LEDs have come and gone. When using a laser diode instead of a traditional LED, you can pump about 2,000 times more electricity into the diode. While this has yet to be tested in practical terms, it could mean that laser diodes are capable of providing 2,000 times as much light. That alone could mark a substantial revolution in worldwide power consumption.
As it always is with the future, of course, we won’t truly know until we get there.
It’s possible that LEDs will become – and remain – the standard for lights throughout the 21st century. It’s also possible, though, that there is another form of lighting technology just waiting to be discovered. As we’ve seen on this brief foray into the History of the LED, we don’t always know change is upon us until it arrives with a bang. And yet, you can’t help but wonder: what will be illuminating the Sistine Chapel in another 500 years?
This Article’s Sources & Suggestions for Further Reading about LEDs: