title: Highly efficient blue organic light-emitting diodes using quantum well-like multiple emissive layer structure.
abstract: In this study, the properties of blue organic light-emitting diodes (OLEDs), employing quantum well-like structure (QWS) that includes four different blue emissive materials of 4,4'-bis(2,2'-diphenylyinyl)-1,1'-biphenyl (DPVBi), 9,10-di(naphth-2-yl)anthracene (ADN), 2-(N,N-diphenyl-amino)-6-[4-(N,N-diphenyl amine)styryl]naphthalene (DPASN), and bis(2-methyl-8-quinolinolate)-4-(phenyl phenolato) aluminum (BAlq), were investigated. Conventional QWS blue OLEDs composed of multiple emissive layers and charge blocking layer with lower highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energy level, and devices with triple emissive layers for more significant hole-electron recombination and a wider region for exciton generation were designed. The properties of triple emissive layered blue OLEDs with the structure of indium tin oxide (ITO) /N,N'-diphenyl-N,N'-bis(1-naphthyl-phenyl)-(1,1'-biphenyl)-4,4'-diamine (NPB) (700 Ǻ)/X (100 Ǻ)/BAlq (100 Ǻ)/X (100 Ǻ)/4,7-diphenyl-1,10-phenanthroline (Bphen) (300 Ǻ)/lithium quinolate (Liq) (20 Ǻ)/aluminum (Al) (1,200 Ǻ) (X = DPVBi, ADN, DPASN) were examined. HOMO-LUMO energy levels of DPVBi, ADN, DPASN, and BAlq are 2.8 to 5.9, 2.6 to 5.6, 2.3 to 5.2, and 2.9 to 5.9 eV, respectively. The OLEDs with DPASN/BAlq/DPASN QWS with maximum luminous efficiency of 5.32 cd/A was achieved at 3.5 V.
authors.affiliation: Department of Green Energy & Semiconductor Engineering, Hoseo University, Asan 336-795, South Korea.
authors.forename: Ju-An
authors.initials: JA
authors.lastname: Yoon
authors.affiliation: Department of Green Energy & Semiconductor Engineering, Hoseo University, Asan 336-795, South Korea.
authors.forename: You-Hyun
authors.initials: YH
authors.lastname: Kim
authors.affiliation: Department of Green Energy & Semiconductor Engineering, Hoseo University, Asan 336-795, South Korea.
authors.forename: Nam Ho
authors.initials: NH
authors.lastname: Kim
authors.affiliation: Department of Green Energy & Semiconductor Engineering, Hoseo University, Asan 336-795, South Korea.
authors.forename: Seung Il
authors.initials: SI
authors.lastname: Yoo
authors.affiliation: Department of Green Energy & Semiconductor Engineering, Hoseo University, Asan 336-795, South Korea.
authors.forename: Sang Youn
authors.initials: SY
authors.lastname: Lee
authors.affiliation: Department of Physics, Hong Kong Baptist University, Hong Kong, China.
authors.forename: Fu Rong
authors.initials: FR
authors.lastname: Zhu
authors.affiliation: Department of Green Energy & Semiconductor Engineering, Hoseo University, Asan 336-795, South Korea.
authors.forename: Woo Young
authors.initials: WY
authors.lastname: Kim
keywords: Blue organic light-emitting diodes; HOMO-LUMO; QWS