Heike Riel left a furniture-making apprenticeship to study physics. A PhD later, she has built the world’s largest full-color display that uses organic light-emitting diodes (OLEDs)- paving the way fro a new generation of vivid-color, affordable , flat-panel televisions and computer monitors. Her 20-inch screen is brighter and more energy efficient than any other screen on the market. Cell-phone displays and other small screens have used OLEDs for streaming video, but larger-scale applications have proven elusive. In a large screen, each of millions of light-emitting pixels requires several transistors, and the transistor matrix had been difficult to manufacture uniformly. Researchers had steadfastly tried to improve the polycrystalline-silicon transistors, claiming that the alternative- amorphous silicon- would break down at the high currents needed for pixel emission, But Riel and her colleagues fashioned the OLEDs at IBM’s Zurich lab so that inexpensive amorphous-silicon transistors drew less current and, therefore, remained particular, tinkered with the width of the pixel’s thin organic layers, allowing significantly more light to be emitted. “People didn’t believe it could be done,” she says.