The Philadelphia area - where TVs were invented by Philo Farnsworth, built by RCA and Philco, and metered by Comcast - remains a hotbed of small-screen development, now that we've moved on to smartphones.

Consumer-electronics factories moved to Asia long ago, and that's where Apple i-devices and rival Android-powered products, successors to yesterday's TVs and personal computers, are made.

But local labs are still pioneers in electronic display. Researchers in Princeton and Wilmington have spent decades developing OLEDS, the thin, flexible, glowing screens increasingly favored by manufacturers.

OLED stands for organic light-emitting diodes. They are not organically alive, nor are they simple electric diodes (unlike, say, LED bulbs). They are films of carbon-based molecules that glow and display electric current into fast, complex, clear, bright patterns, for movies or data feeds. Fans say they use less energy than standard liquid-crystal displays (LCDs), and waste less heat than LEDs.

DuPont Co. researchers in Wilmington and Newark, Del., have been working on mass-production OLED manufacturing systems since the 1990s. Scientists at Universal Display, a Ewing Township, Mercer County, firm, founded by a group of Philadelphia entrepreneurs, since 1994 has developed, bought or applied for 3,600 OLED patents in the United States, Europe, and the factory countries of Asia.

Burning more than $200 million in investor and research cash in its first 17 years, Universal Display turned profitable in 2011, after the company licensed Samsung to use its OLED recipes and materials to build screens for Galaxy smartphones, powered by Google Android software. A gram of material can build 1,000-plus screens.

Profits topped $120 million from 2012 to 2015, rising each year. With both Samsung and the firm's other main client, LG Display, "ramping production" at their South Korea factories, revenue should grow by at least $80 million in each of the next three years, above last year's $200 million, said projects analyst Robert W. Stone, of Cowen & Co.

"This industry is in its infancy," said Universal Display chief executive Steve Abramson. "From smartphones like Samsung Galaxy, we have gone to wearables like the iWatch, and now TVs. We are a key supplier to what is still a very small portion of the world display market. We will be extending our lead."

World appetite for OLEDs is expected to grow from 1.5 million square meters of screens, worth $9 billion, in 2014, to $23 billion and 12 million square meters by 2020, as prices drop, said business-

analytics firm IHS Inc.

Universal Display sales could grow far faster, Stone says - if Apple uses Universal Display OLEDs in its iPhone 8's to replace liquid-crystal displays, or Audi adopts a proposed OLED auto display panel, or glare-free OLED TVs take off, or lighting companies mass-

produce OLED lamps.

Investors are uncertain: After zooming to $60 in 2011, Universal Display shares have dipped on China recession rumors and rebounded on deal gossip. "Adoption is never as fast as anyone anticipates," warns Darice Liu, who followed the stock as a Needham & Co. analyst before joining Universal Display as investor-relations chief.

Universal Display engineers and scientists, at its 120-worker Ewing headquarters and in contracted university labs at Princeton, Michigan and the University of Southern California, develop new OLED recipes and materials; chemists and lab workers build samples; and PPG Industries plants in Western Pennsylvania and Ohio scale production of the firm's OLED materials in powder form, so Samsung and LG can build them into screen sheets in a vacuum process.

Abramson and chief financial officer Sid Rosenblatt were lured to Universal Display by founder Sherwin Seligsohn, a self-taught investor who started the company after his ouster from his earlier mobile-phone and patent-licensing firm, now known as InterDigital. Seligsohn, 79, remains Universal Display's chairman.

Rosenblatt says Universal Display stokes loyalty with stock-options grants and a deal that pays 3 percent of revenues to its university research partners, which split the money with researchers. Options "are why our parking lot looks like Stuttgart," says Rosenblatt, who, like Abramson, commutes daily from the Main Line. The pair met at Temple Law School.

Will electronics factories ever return to Philadelphia? "Display manufacturing is tough," says Abramson. He noted that LG committed billions for an OLED big-screen TV plant in Korea, to open in 2018. "No one in the U.S. will spend that much," Abramson said.

But OLED lighting may be different, he added. The lamps - samples in Universal Display's labs burn cool to the touch, at room temperature - are less elaborate to build.

"Lighting is traditionally a local industry," he said. "Once we get the costs down, if the U.S. develops a manufacturing mindset again, I think we'll see these made here."