Lithium phenolate complexes for an electron injection layer in organic light-emitting diodes

✍ Scribed by Yong-Jin Pu; Masashi Miyamoto; Ken-ichi Nakayama; Toshiro Oyama; Yokoyama Masaaki; Junji Kido

• Publisher: Elsevier Science
• Year: 2009
• Tongue: English
• Weight: 278 KB
• Volume: 10
• Category: Article
• ISSN: 1566-1199
• DOI: 10.1016/j.orgel.2008.11.003

✦ Synopsis

We synthesized p-conjugated lithium phenolate complexes, lithium 2-(2-pyridyl)phenolate (LiPP), lithium 2-(2 0 , 2 00 -bipyridine-6 0 -yl)phenolate (LiBPP), and lithium 2-(isoquinoline-1 0 -yl)phenolate (LiIQP). These complexes showed lower sublimation temperatures of 305-332 °C compared to 717 °C of LiF. The organic light-emitting devices (OLEDs) using these complexes as an electron injection layer exhibited high efficiencies which are comparable to that of the device using LiF. Especially, a 40-nm thick film of LiBPP or LiPP was effective as an electron injection material, providing low driving voltages, while such a thick film of LiF serves as a complete insulator, resulting in high driving voltages.