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Solar Power's Surprise ; Cell Created 50 Years Ago Inspired Invention

Posted on: Thursday, 29 April 2004, 06:00 CDT

Fifty years ago this week, scientists at Bell Labs unveiled a small device built with a jeweler's precision that turned the sun's energy into electricity.

They called it a "solar battery."

The company assembled on the front lawn of Bell Labs' Murray Hill headquarters to announce creation of the world's first commercially viable solar cell.

"An amazingly simple-looking apparatus made of strips of silicon showed how the sun's rays could be used to power ... a transistor radio transmitter carrying both speech and music," the company wrote in a press release.

At the time, some pundits believed that solar power would one day provide for the world's energy needs.

But it didn't happen that way.

Despite its recent rapid growth, solar power today accounts for less than 1 percent of the world's energy production.

However, that tiny solar cell, about the size of a small stick of gum, was the starting point for a whole range of inventions based on photo detection, the solar cell's underlying technology.

Everything from DVD players to the Internet uses some type of photo detector.

"You can trace the roots back to the work that went into the solar cell," said Bell Labs spokesman Rich Teplitsky.

The 1954 trio of Bell Labs scientists - physicist Gerald Pearson, chemist Calvin Fuller, and electrical engineer Daryl Chapin - who worked on the commercial solar cell were followed about 15 years later by another pair from Bell Labs who came up with something called the charge-coupled device, or CCD.

Using the solar cell's photo detection principle, researchers George Smith and Willard Boyle invented the CCD, which converted light into a digital signal.

This invention led to a range of devices and technologies such as digital cameras, camcorders, high-definition television, security monitoring, medical endoscopy, and video conferencing.

The Internet grew in part because of the high-capacity fiber optic cables that carry the massive streams of data. And those fiber optic lines transmit data across the network using light.

At the receiving end of these so-called optical networks is the modern version of the photo detector, which converts light back into electrical signals that can be interpreted by a computer.

At the time Bell Labs invented the solar cell, it was part of the nation's monopoly phone company, AT&T. Bell Labs spun off from AT&T in 1996 as part of Lucent Technologies.

Like the transistor, invented by Bell Labs in 1947, the company did not take out a patent on the solar cell, instead releasing the technology for public use.

These days, Bell Labs researchers are working on photo detector applications including system-on-a-chip technology that could, the company says, lead to ultra-high-speed communications delivered via fiber optic line to individual homes.

To be sure, solar energy hasn't stood still in the past half- century.

The very first solar cell (also invented at Bell Labs in 1941 by R.-S. Ohl) was not particularly efficient.

The 1954 version, however, was capable of producing a single watt of power. It achieved a 6 percent efficiency converting the sun's energy to electricity, a rate comparable to that era's gas and steam engines.

The Solar Energy Industries Association expects that solar panels manufactured this year will be capable of producing 1 billion watts, enough to power 400,000 homes.

Solar energy panels also have been used on every space vehicle, including the International Space Station and the Mars Rovers.

"There are lots of examples of things that could not be done without solar cells," said Alice White, director of Integrated Photonics Research at Lucent Technologies' Bell Labs.

The Telstar I, the world's first communications satellite, was launched in 1962 carrying 3,600 Bell Labs solar "batteries."

Although solar panels aren't standard features on suburban roofs, most people in the United States are at least familiar with solar, courtesy of devices such as calculators or emergency roadside assistance phones.

"The solar cell is the unsung hero," Teplitsky said.

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