Universal Display (Ewing, N.J.) will provide its organic materials and Sony its device technologies, the companies said, including low-temperature polysilicon thin-film transistors and a top-emission scheme.

By merging their technologies, the partners intend to improve emission efficiency and lifetime of the OLED. No development schedule was disclosed.

While other OLED players depend on fluorescent emission, Universal Display's materials — which were jointly developed with partner PPG Inc. (Pittsburgh) — emit light through the process of phosphorescence. Theoretical and experimental estimates put the upper limit of efficiency of an OLED doped with fluorescent material at approximately 25 percent, Universal Display said. By contrast, an OLED that uses its phosphorescent materials as a dopant has the potential of 100 percent efficiency, according to the company.

Hiroyuki Yoshida, senior analyst at Wit Capital Japan Inc., said that phosphorescent emission had the potential to deliver innovation to the OLED market.

Sony demonstrated a very thin active-matrix 13-inch OLED display prototype last February. The company pinpoints OLED and field-emission displays as technologies with big potential in TVs.

'Top' efficiency

Sony's drive technology, called top-emission adaptive-current (TAC) drive, differs from the bottom emission used in most OLED displays. "The top emission is desirable because all circuitry can be placed at the bottom," yielding a gain in efficiency, said an engineer of a leading OLED developer.

In the conventional OLED display, light is emitted through the glass substrate, which is the bottom emission structure. Sony's display uses a transparent cathode on the opposite side of the glass substrate, on which the transistor, wiring layer and metal anode are fabricated.

Light generated at the emitting layer radiates upward through the transparent cathode and seal, without any interference from components such as wiring and transistors.