title: Transparent amorphous oxide semiconductors for organic electronics: Application to inverted OLEDs.
abstract: Efficient electron transfer between a cathode and an active organic layer is one key to realizing high-performance organic devices, which require electron injection/transport materials with very low work functions. We developed two wide-bandgap amorphous (a-) oxide semiconductors, a-calcium aluminate electride (a-C12A7:e) and a-zinc silicate (a-ZSO). A-ZSO exhibits a low work function of 3.5 eV and high electron mobility of 1 cm2/(V · s); furthermore, it also forms an ohmic contact with not only conventional cathode materials but also anode materials. A-C12A7:e has an exceptionally low work function of 3.0 eV and is used to enhance the electron injection property from a-ZSO to an emission layer. The inverted electron-only and organic light-emitting diode (OLED) devices fabricated with these two materials exhibit excellent performance compared with the normal type with LiF/Al. This approach provides a solution to the problem of fabricating oxide thin-film transistor-driven OLEDs with both large size and high stability.
authors.affiliation: Materials Research Center for Element Strategy, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8503, Japan; hosono@msl.titech.ac.jp.|Laboratory for Frontier Materials, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8503, Japan.|ACCEL Program, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi 332-0012, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Hosono
authors.affiliation: Materials Research Center for Element Strategy, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8503, Japan.|ACCEL Program, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi 332-0012, Japan.
authors.forename: Junghwan
authors.identifier: 0000-0001-9168-6260
authors.initials: J
authors.lastname: Kim
authors.affiliation: Materials Research Center for Element Strategy, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8503, Japan.|ACCEL Program, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi 332-0012, Japan.
authors.forename: Yoshitake
authors.initials: Y
authors.lastname: Toda
authors.affiliation: Materials Research Center for Element Strategy, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8503, Japan.|Laboratory for Frontier Materials, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8503, Japan.
authors.forename: Toshio
authors.initials: T
authors.lastname: Kamiya
authors.affiliation: ACCEL Program, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi 332-0012, Japan.|Research Center, Asahi Glass Co. Ltd., 1150 Hazawa, Kanagawa, Yokohama 221-8755, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Watanabe
keywords: amorphous oxide semiconductor; electron injection; electron transport; inverted OLEDs; low work function material