title: Highly Simplified Tandem Organic Light-Emitting Devices Incorporating a Green Phosphorescence Ultrathin Emitter within a Novel Interface Exciplex for High Efficiency.
abstract: Herein we report a novel design philosophy of tandem OLEDs incorporating a doping-free green phosphorescent bis[2-(2-pyridinyl-N)phenyl-C](acetylacetonato)iridium(III) (Ir(ppy)2(acac)) as an ultrathin emissive layer (UEML) into a novel interface-exciplex-forming structure of 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC) and 1,3,5-tri(p-pyrid-3-yl-phenyl)benzene (TmPyPB). Particularly, relatively low working voltage and remarkable efficiency are achieved and the designed tandem OLEDs exhibit a peak current efficiency of 135.74 cd/A (EQE = 36.85%) which is two times higher than 66.2 cd/A (EQE = 17.97%) of the device with a single emitter unit. This might be one of the highest efficiencies of OLEDs applying ultrathin emitters without light extraction. Moreover, with the proposed structure, the color gamut of the displays can be effectively increased from 76% to 82% NTSC if the same red and blue emissions as those in the NTSC are applied. A novel form of harmonious fusion among interface exciplex, UEML, and tandem structure is successfully realized, which sheds light on further development of ideal OLED structure with high efficiency, simplified fabrication, low power consumption, low cost, and improved color gamut, simultaneously.
authors.affiliation: Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University , Suzhou, Jiangsu 215123, China.|School of Advanced Materials, Shenzhen Graduate School, Peking University , Shenzhen 518055, China.
authors.forename: Ting
authors.initials: T
authors.lastname: Xu
authors.affiliation: Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University , Suzhou, Jiangsu 215123, China.
authors.forename: Jun-Gui
authors.initials: JG
authors.lastname: Zhou
authors.affiliation: Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University , Suzhou, Jiangsu 215123, China.
authors.forename: Chen-Chao
authors.initials: CC
authors.lastname: Huang
authors.affiliation: Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University , Suzhou, Jiangsu 215123, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University , Suzhou, Jiangsu 215123, China.
authors.forename: Man-Keung
authors.initials: MK
authors.lastname: Fung
authors.affiliation: Key Laboratory of Flexible Electronics and Institute of Advanced Materials, Jiangsu National Synergistic Innovation Centre for Advanced Materials, Nanjing Tech University , Nanjing 211816, China.|Department of Physics, International Islamic University , Islamabad 44000, Pakistan.
authors.forename: Imran
authors.identifier: http://orcid.org/0000-0001-5322-8656
authors.initials: I
authors.lastname: Murtaza
authors.affiliation: School of Advanced Materials, Shenzhen Graduate School, Peking University , Shenzhen 518055, China.|Key Laboratory of Flexible Electronics and Institute of Advanced Materials, Jiangsu National Synergistic Innovation Centre for Advanced Materials, Nanjing Tech University , Nanjing 211816, China.
authors.forename: Hong
authors.identifier: http://orcid.org/0000-0001-5877-359X
authors.initials: H
authors.lastname: Meng
authors.affiliation: Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University , Suzhou, Jiangsu 215123, China.
authors.forename: Liang-Sheng
authors.identifier: http://orcid.org/0000-0002-2352-9666
authors.initials: LS
authors.lastname: Liao
keywords: current efficiency; interface exciplex; organic light-emitting diodes; tandem structure; ultrathin emissive layers