But making large OLED screens has proved difficult.
Proponents have hoped they could potentially replace liquid crystal display (LCD) and plasma TVs.
"The reality is that OLED will come one day as an additional technology for flat displays. I say this with a lot of confidence," the head of Merck's chemicals business, Walter Zywottek, told Reuters in an interview.
Merck, the world's largest supplier of liquid crystals for use in TVs, notebook and mobile phones, dominates the high-tech niche industry with about two thirds of the liquid crystal market.
Top LCD makers such as Samsung Electronics, LG Philips LCD, Sharp Corp. and AU Optronics are its customers.
The LCD makers have invested about $82 billion in plant capacity over the past 11 years. In 2008, some $28 billion in new investments has been announced. In contrast, plasma screen makers invested about $12 billion over the last decade.
"Forget replacement. Delete replacement from your vocabulary, it's not going to happen. Would you be spending so much money if you were thinking about replacement?" he asked.
He said any serious commercial OLED application would not arrive before 2010.
Zywottek said Merck is also boosting its investment in OLED but is not expecting it to play the role that liquid crystals now have at the company.
"It will not be one dominating supplier in OLED. Not a single supplier will have such a strong position as we have in liquid crystals," he said.
"There will be different companies with different materials and we will be one of them," he added.
Zywottek said more than 100 researchers have been working on OLED technology for a couple of years at Merck.
Merck announced it is investing 47 million euros in a new research and development centre at its Darmstadt headquarters for the chemicals business, including for OLED.
This is its largest single investment to date in chemicals research and development.
Sony Corp. showcased its OLED TVs this year and will start selling an 11-inch version of the 3-millimeter thick TV for about $2,000.