Phosphorescent-based OLED panels ready for volume production

Organic light-emitting devices (OLED) employing phosphorescent materials are poised to enter volume production for the first time.

Tohoku Pioneer, a subsidiary of Pioneer Corp., which was the first manufacturer to introduce OLED panel products in 1999, said it has signed a contract with Universal Display Corp. (UDC) to supply phosphorescent material for OLED panels.

Tohoku Pioneer will use UDC's trademarked PhoLED material to improve the purity of red color in its passive-matrix OLED displays. Volume production will begin by the end of the year.

Conventional OLED panels use fluorescent materials to generate red, green, and blue light. The materials doped with fluorescent materials take only the singlet excited state and have the efficiency to convert electric energy to light at the maximum rate of 25 percent. On the other hand, doping with phosphorescent materials exploit both singlet and triplet excited states, offering the potential of 100-percent efficiency, UDC said.

Tohoku Pioneer and the laboratory of its parent company have been working to introduce phosphorescent materials for its OLED volume production process. The company said it has "achieved the level targeted for volume production," according to a Tohoku Pioneer spokesman.

"Even some of fluorescent materials emit red in high purity, but the lifetime is too short for products. The phosphorescent material is a practically usable material that emits highly pure red," the spokesman added.

UDC has been working with several partners to develop OLED panels using phosphorescent materials. The closest partner is Sony, with which UDC signed a joint development contract in April 2001. Sony has been developing OLEDs with the material for large-screen TV applications.

- Yoshiko Hara

EE Times