title: Synergetic electrode architecture for efficient graphene-based flexible organic light-emitting diodes.
abstract: Graphene-based organic light-emitting diodes (OLEDs) have recently emerged as a key element essential in next-generation displays and lighting, mainly due to their promise for highly flexible light sources. However, their efficiency has been, at best, similar to that of conventional, indium tin oxide-based counterparts. We here propose an ideal electrode structure based on a synergetic interplay of high-index TiO2 layers and low-index hole-injection layers sandwiching graphene electrodes, which results in an ideal situation where enhancement by cavity resonance is maximized yet loss to surface plasmon polariton is mitigated. The proposed approach leads to OLEDs exhibiting ultrahigh external quantum efficiency of 40.8 and 62.1% (64.7 and 103% with a half-ball lens) for single- and multi-junction devices, respectively. The OLEDs made on plastics with those electrodes are repeatedly bendable at a radius of 2.3 mm, partly due to the TiO2 layers withstanding flexural strain up to 4% via crack-deflection toughening.
authors.affiliation: School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea.|Graphene Research Center, KI for Nanocentury, KAIST, Daejeon 305-701, Republic of Korea.
authors.forename: Jaeho
authors.initials: J
authors.lastname: Lee
authors.affiliation: Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyungbuk 790-784, Republic of Korea.
authors.forename: Tae-Hee
authors.initials: TH
authors.lastname: Han
authors.affiliation: Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyungbuk 790-784, Republic of Korea.
authors.forename: Min-Ho
authors.initials: MH
authors.lastname: Park
authors.affiliation: School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea.|Graphene Research Center, KI for Nanocentury, KAIST, Daejeon 305-701, Republic of Korea.
authors.forename: Dae Yool
authors.initials: DY
authors.lastname: Jung
authors.affiliation: Department of Mechanical Engineering, KAIST, Daejeon 305-701, Republic of Korea.
authors.forename: Jeongmin
authors.initials: J
authors.lastname: Seo
authors.affiliation: Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyungbuk 790-784, Republic of Korea.
authors.forename: Hong-Kyu
authors.initials: HK
authors.lastname: Seo
authors.affiliation: School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea.|Graphene Research Center, KI for Nanocentury, KAIST, Daejeon 305-701, Republic of Korea.
authors.forename: Hyunsu
authors.initials: H
authors.lastname: Cho
authors.affiliation: School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea.|Graphene Research Center, KI for Nanocentury, KAIST, Daejeon 305-701, Republic of Korea.
authors.forename: Eunhye
authors.initials: E
authors.lastname: Kim
authors.affiliation: School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea.|Graphene Research Center, KI for Nanocentury, KAIST, Daejeon 305-701, Republic of Korea.
authors.forename: Jin
authors.initials: J
authors.lastname: Chung
authors.affiliation: School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea.|Graphene Research Center, KI for Nanocentury, KAIST, Daejeon 305-701, Republic of Korea.
authors.forename: Sung-Yool
authors.initials: SY
authors.lastname: Choi
authors.affiliation: Department of Mechanical Engineering, KAIST, Daejeon 305-701, Republic of Korea.
authors.forename: Taek-Soo
authors.initials: TS
authors.lastname: Kim
authors.affiliation: Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyungbuk 790-784, Republic of Korea.
authors.forename: Tae-Woo
authors.initials: TW
authors.lastname: Lee
authors.affiliation: School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea.|Graphene Research Center, KI for Nanocentury, KAIST, Daejeon 305-701, Republic of Korea.
authors.forename: Seunghyup
authors.initials: S
authors.lastname: Yoo