When it comes to lighting, though, we’re stuck in the past. The incandescent light bulb that you probably have in your bedside lamp is based on the same technology invented by Thomas Edison more than a century ago. Electricity flows into a metal filament, and the filament heats up and emits light as a byproduct.

Now, the same technology that forms the basis for our computers is set to revolutionize electric lighting as well. It’s known as solid-state lighting, and it has the potential to transform the way we use light.

Light from Computers

Computer chips are made up of what are known as semiconductors. These are solid materials (such as silicon) that can carry an electrical current but, unlike regular conductors like copper wire, can also be easily turned off so that electricity will not flow through it.

LEDs and their organic cousins, OLEDs, will one day make our homes and offices much brighter, while using less energy.

RPI Lighting Res. Center

Solid-state lighting includes two similar technologies: light-emitting diodes (LEDs) and organic light-emitting diodes (OLEDs). A diode is a simple form of a semiconductor, so both LEDs and OLEDs are like tiny computer chip parts that give off light.

Both technologies are composed of layers: one is negatively charged, and one is positively charged. When electric current flows through the diode, it excites negatively charged particles, or electrons, in one layer and causes them to fall into holes in the other layer. The energy released in that fall is emitted as light. The color of the LED depends on the material used in the layers and the distance the electrons fall.

Why LEDs?

We don’t think about it much when we flick on the lights, but keeping our houses lit uses up roughly 10 percent of all the electricity we use in homes. Add the lighting needs of businesses and the percentage is even higher. Incandescent light-bulbs are horribly inefficient: only about 5 percent of the energy goes into creating light. The rest is wasted as heat. Fluorescent bulbs are more efficient and last longer, but the toxic mercury in the bulbs means they have to be thrown out in special collections.

Depending on the color, LEDs are 20 to 50 percent efficient, so they save a tremendous amount of energy. The rest of the energy becomes heat, but they’re not hot to touch like incandescent bulbs. Researchers at Sandia National Lab estimate that within a little more than a decade, LEDs could cut the energy used for lighting in half!

LEDs also produce more than 70,000 hours of light — they last a long, long time. And they’re encased in plastic, not glass, so they’re nearly impossible to break.

These digital lights have already replaced traditional bulbs in traffic lights and in displays on clocks and cell phones. They’re used to colorfully light up bridges at night, and for larger-than-life videos, such as the enormous sign that hangs on the corner of a building in New York’s Times Square.

White LEDs are still too expensive to replace all our home and office lighting. But they make great camping flashlights, because they’re bright, tiny, energy-efficient, long-lasting, unbreakable, and can be powered by rechargeable batteries.

Many poor people around the world have no electricity in their homes, so they rely on expensive and polluting kerosene lamps. The same characteristics that make LEDs perfect for camping lights also make them ideal an ideal way to provide light for families who have never owned a bulb.

Groups such as the Light up the World Foundation have designed LEDs, powered by renewable energy, for people who lack electricity. Suddenly, children can study at night, and parents can keep working into the evening. LEDs have already improved the lives of thousands of people around the world!

The firm Kennedy and Violich Architecture created a fabric woven with tiny LEDS for a community in Mexico. It can be worn as a bag during the day, and turns into a lamp at night. (Read more about how it works here.)

New Ideas in Lighting

Imagine a room where you could push a button and change the color of the light. LEDs come in red, green and blue. Each one can be the size of a dot, and when those dots are combined, they can be lit up in different combinations to create an endless variety of colors. Companies have created LEDs that flow from one color to another, all through the rainbow.

“With the touch of a button you can create pretty much any color scheme,” explains Nadarajah Narendran, research director at the Lighting Research Center of Rensselaer Polytechnic Institute. “You could change the color in your room to suit your mood.”

Designers are developing new ways to use LEDs in a building. Light glows from a tile on the floor, or a panel on the wall. (This is hard to do with the breakable glass bulbs used today.) These tiles have already been built, but they don’t fit the standard systems in houses today, where bulbs get screwed into sockets. Narendran says that houses would have to be designed differently to create the right wiring for these blocks of light. He has some lighting up his lab!

But the uses of LEDs don’t end with indoor and outdoor light. Babak Parviz, a scientist at the University of Washington, is designing special lenses that use dust-sized particles of LEDs to display information. Parviz wants to create futuristic contact lenses that could sense changes in your body, such as from a disease, and notify you on the corner of the lens. These don’t exist yet, but someday you might be able to read information broadcast by LEDs literally right in front of your eyes.

LEDs, the Next Generation

LEDs are manufactured in the same manner as computer chips. The materials are deposited in very thin layers under extremely hot temperatures, as high as almost 1,000 degrees Fahrenheit. That costs a great deal of money. They’re also based on the material silicon, the same material that forms the basis for computer semiconductors.

OLEDs function similarly to LEDs, however, they can be manufactured much more easily; use even less power, and can be made extremely thin to be used on paper or even fabric.

Yogurt6255520 / Wikimedia Commons

Organic LEDs (OLEDs), on the other hand, have a carbon base instead of a silicon base. (Carbon forms the building-blocks of life on earth, which is why these are called “organic.”)They work in somewhat the same way as LEDs do: a current flows into the material, one layer gives off electrons, and those electrons fall into another layer. Then there’s a layer that transmits that energy into light we can see. The color of the light depends on the material in that final layer, and most OLEDs have different layers that emit different colors.

Unlike those super high LED manufacturing temperatures, OLEDs can be created at room temperature, which is significantly cheaper. Layers are deposited on a surface, as ink is layered on paper. OLEDs are also extremely thin and can be potentially printed on any substance, even paper or fabric.

“This flexibility is what makes people dream about all the different ways to use OLED technology,” says Bernard Kippelen, an OLED researcher at the Georgia Institute of Technology in Atlanta.

With OLEDs, Narendran imagines entire wall-sized sheets. He says, “You could hang one up and change lighting designs easily, like a shifting wallpaper of light design.” Because OLEDs are transparent when they’re off, a window covered by an OLED could glow brightly when night comes. Or a shimmering picture could be printed directly on a T-shirt.

OLEDs are used today in cell phone screens, but most of those other ideas are still in the design phase. Recently, though, Sony showed off the world’s very first OLED television. It’s only 11 inches large, and it costs about $2,500. It’s incredibly thin, only 3 millimeters at its widest spot — thinner than your finger from front to back — and uses about 40 percent less energy than other thin-screen televisions. The colors and picture are said to be some of the best yet. But with an expensive price-tag, and because it can’t yet be easily scaled up into a bigger screen, it may take years before you buy an OLED TV for the living room.

The path ahead

There are still challenges to overcome before solid-state lighting replaces all the bulbs in our sockets. Scientists are investigating ways to make both LEDs and OLEDs still more efficient and cheaper. The organic materials in OLEDs are fragile and don’t last as long as traditional LEDs, so scientists are looking for ways to make them sturdier. Plus, moisture harms OLEDs, so researchers are trying to figure out how to protect these lights of the future.

Kippelen says the scientists at his lab, like others around the world, are the innovators who are advancing the technology. But as for all the potential uses, Kippelen says, “I leave it to artists and designers to predict what can be done.”

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To help support themselves, the Huichol create beautiful artwork, including paintings made from yarn and sculptures made from beads. They sell their art in cities hundreds of miles away from their villages. Often, they travel long distances by foot. And without electricity—at home or on the road, they can only work during daylight hours.

Portable lights are bringing much-needed light to the Huichol people, who live in the beautiful and rugged Sierra Madre of Mexico.Huichol art is full of symbols and meaning. This traditional yarn painting (above) was made by Huichol artist Rojelio Beuites

Stephanie/Wikipedia

When it gets dark, they must stop whatever they’re doing, explains Huichol community leader Miquel Carillo. The sales of their artwork are essential to this economy, where farming is difficult and crops often fail.

“We can only work during the day,” Carillo tells a group of researchers as night approached. “Because now, as you see, we can’t see anything, and it’s still so early. Nobody can do anything. We just wait for the sun to come up again.”

Now, a team of scientists, designers, and architects is using new technologies to provide the Huichol with light after the sun sets—no plugs necessary. The scientists’ technique involves weaving tiny electronic crystals into fabrics that can be made into clothes, bags, or other items.

A Huichol woman weaves new, light-producing technology into a traditional cloth bag.

Kennedy & Violich Architecture, Ltd.

By collecting the sun’s energy during the day, these lightweight textiles provide bright white light at night. Their inventors have named the textiles “Portable Lights.”

Portable Lights have the potential to transform the lives of people without electricity around the world, says project leader Sheila Kennedy, head of Kennedy & Violich Architecture, Ltd., in Boston, Mass.

“Our invention,” Kennedy says, “came from seeing how we could transform technology we saw everyday in the United States and move it into new markets for people who didn’t have a lot of money.”

As part of the Portable Light Project, Kennedy and colleagues have already donated light-producing textiles to two Huichol communities. They are working now with a group of wandering, or semi-nomadic, people in Australia. Eventually, they hope to deliver Portable Lights to similar groups around the world.

See the light

At the core of Portable Light technology are devices called high-brightness light-emitting diodes, or HB LEDs. These tiny lights appear in digital clocks, televisions, streetlights, and the blinking red lights on some sneakers.

LEDs are completely different from the light bulbs that you screw into lamps at home. Most of those glass bulbs belong to a type called incandescent lights. Inside, electricity heats a metal coil to about 4,000 degrees Fahrenheit, or 2,200 degrees Celsius. At that scorching temperature, bulbs give off light we can see.

In an incandescent light bulb, like the one above, electricity heats a metal coil until it becomes extremely hot and gives off light.

Wikipedia/Tomasz Sienicki

Ninety percent of energy produced by incandescent lights, however, is heat–and invisible. With all that wasted energy, bulbs burn out quickly. They are also bulky, can get hot, and are easily broken.

LEDs, on the other hand, are like tiny pieces of rock made up of molecules that are arranged in a crystal structure. When an electric current passes through an LED, the crystal structure vibrates and produces light.

Unlike incandescent bulbs, they can produce light of various colors. Within an LED, the type of molecules and their particular arrangement determines what color is produced.

For example, green LEDs make up the blinking, hand-shaped signals that tell pedestrians when it’s safe to cross a street. LEDs in a remote control, on the other hand, give off invisible infrared light that tells a television to change channels.

Light-emitting diodes come in a variety of sizes and colors. What they all share in common is their tiny size compared to incandescent bulbs. The purple-colored LED in the lineup above emits infrared light.

Wikipedia

LEDs are tiny and extremely lightweight. There are no breakable glass parts. While the technology is still somewhat expensive, researchers are increasingly looking to LEDs for a wide variety of applications, including Portable Lights.

“A lot of people see LEDs as being the future of lighting,” says Casey Smith, a technologist in Bozeman, Mont., and a member of the Portable Light team. He developed much of the technology that make Portable Lights work.

The spark

The Portable Light team found a way to weave two LEDs into a plastic-coated textile. When turned on, these LEDs can make the entire piece of fabric glow.

Their next challenge was to figure out how to power the LEDs without electricity. The researchers knew that they wanted to tap the sun’s energy, but they couldn’t use standard solar panels such as those found on rooftops. These bulky glass panels would be too big and heavy for the Huichol to carry as they traveled through the mountains.

Instead, the researchers used a new type of solar panel, which is flat and flexible, like a placemat. Just 10 inches long and 5 inches wide, these panels can be easily sewn onto a piece of fabric.

A Mexican boy who lives in the Sierra Madre carries a woven bag, complete with LED’s and a solar panel.

Kennedy & Violich Architecture, Ltd.

Circuits connect the solar panel to a lithium ion battery—the type of battery found in laptops and cellular phones. And the battery, in turn, is connected to the two LEDs in the fabric. A tough layer of plastic protects the circuitry.

With just 3 hours of exposure to sunlight, the battery accumulates enough charge to power a portable light for 10 hours, Kennedy says. A membrane switch, like the soft buttons on a microwave oven, allows a user to turn the lights on or off.

Portable light technology provides enough light for this Huichol girl to do her homework at night, even though there is no electricity in her village.

Kennedy & Violich Architecture, Ltd.

A Portable Light weighs less than a pound and can withstand abuse because textiles are strong for their weight. Kennedy has dropped Portable Light units from as high as 30 feet off the ground without damaging them.

“With no heavy parts to break, they just float down,” she says.

Lighting the way

The Huichol have quickly accepted Portable Light technology by incorporating it into their cultural traditions.

Huichol women have long woven colorful bags on a handmade device called a backstrap loom. They use these bags to tote their belongings because their traditional clothing does not have pockets.

Each bag contains intricate patterns and symbols that reflect cultural stories and family identities. Bags and patterns are passed from generation to generation.

“It is more than just a bag,” Kennedy says. “It is vital to their life.”

Portable lights are bringing much-needed light to the Huichol people, who live in the beautiful and rugged Sierra Madre of Mexico.

Tim&Annette/Wikipedia

The Huichol are now weaving Portable Lights into new patterns in their bags, Kennedy says. And the researchers on the Portable Light team can’t keep up with demand. More than 40 women have put their names on a waiting list.

On the other side of the world, in the Central Australian desert, Kennedy and colleagues are working to bring Portable Lights to the Arrernte people, who travel across large stretches of desert without electricity.

One goal is to use the technology to power cell phones that teachers in local schools can use to download lesson plans. That way, Kennedy says, kids won’t have to travel to cities to get an education.

It may be hard to imagine life without access to lights at night. As the Portable Light project expands, researchers hope that fewer and fewer people will have that problem.

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