Osram has joined the race to develop OLEDs for the mass market of general lighting applications.

“In a few years we will see first OLED lighting products which will penetrate the lighting market more and more as the technology matures,” Osram strategic marketer Marion Reichl told EW.

In looking at OLEDs to replace light fittings, the firm is moving in the same direction as Thorn Lighting, which discussed OLED office lighting at a recent UK Lighting and Displays Knowledge Transfer Network meeting (EW 26 July, 2006).

Osram has chosen to start on the vapour-deposited small-molecule OLED route for its lighting research. “For displays we are standardly using polymer OLED technology with wet process deposition,” said Reichl, “whereas for lighting we are currently focusing on small molecules by evaporation.”

Initially luminairs will use glass substrates. “In parallel, we are working on alternative substrate technologies enabling unique features and low cost, of which details cannot be revealed at the moment,” said Reichl.

Moving away from glass substrates means moisture and oxygen ingress becomes an issue. “We are currently working on improving both materials’ stability against moisture as well as improving the encapsulation,” Reichl said.

Domestic light bulbs offer 12lm/W efficiency, halogen lights somewhere near 18lm/W. The fluorescent lights used in offices produce 50lm/W, with premium types exceeding 100lm/W.

Initial research findings at Osram show 25lm/W at low current and 18lm/W “at brightness levels that are matched to general lighting applications”, it said.

As soon as OLED are on par with halogen lamps, applications can be served, said Reichl.

“But to enter the general lighting market, efficiencies of 50lm/W and above are required. With recent publications of R&D results worldwide of 30-50lm/W we are confident we can reach these values,” she said.