South Korea’s LG Display Co. and LG Chem Ltd. have domestically produced a core material for organic light-emitting diode (OLED) that they previously had to depend entirely on imports.

Both LG Group affiliates on Monday announced their joint development of p-type dopants, or compounds added to OLED’s self-illuminating emissive layer to raise luminous efficacy and cut power consumption. This breakthrough was far from easy as the material easily deteriorates in the air.

This was the result of joint research by the two companies over the last 10 years under the goal of localizing the compound. They used domestic technology to create a material with the same efficiency and performance as imports.

LG Display proposed the design and verified the performance of p-dopant, while LG Chem synthesized and produced it. The former also set up a stable supply chain through domestic production of the compound and secured its own patents, two factors expected to raise the profiles of both companies on the global OLED market.

LG Display has pursued homegrown output of materials, parts and equipment with domestic partners. It has transferred about 5,000 of its patents to second- and third-tier partners either for free or for a fee.

Over 30 joint R&D projects conducted every year have helped such partners maintain technological competitiveness. Thus the localization rate for OLED materials rose from 58% last year to 64% this year.

“Since mass-producing the world’s first 55-inch OLED TV panel in 2013, we’ve raised our technological capacity over the past 10 years,” LG Display Chief Technology Officer and Vice President Yoon Soo-young said. “With this technology, we’ve boosted our leadership in OLED technology as our independent development extends even to core materials.”