title: Highly Efficient Deep-Blue Electroluminescence from a Charge-Transfer Emitter with Stable Donor Skeleton.
abstract: Organic materials containing arylamines have been widely used as hole-transporting materials as well as emitters in organic light-emitting devices (OLEDs). However, it has been pointed out that the C-N bonds in these arylamines can easily suffer from degradation in excited states, especially in deep-blue OLEDs. In this work, phenanthro[9,10-d]imidazole (PI) is proposed as a potential donor with higher stability than those of arylamines. Using PI as the donor, a donor-acceptor type deep-blue fluorophore 1-phenyl-2-(4″-(1-phenyl-1H-benzo[d]imidazol-2-yl)-[1,1':4',1″-terphenyl]-4-yl)-1H-phenanthro[9,10-d]imidazole (BITPI) is designed and synthesized. Results from UV-aging test on neat films of BITPI and other three arylamine compounds demonstrate that PI is indeed a more stable donor comparing to common arylamines. An OLED using BITPI as an emitter exhibits good device performances (EQE over 7%) with stable deep-blue emission (color index: (0.15, 0.13)) and longer operation lifetime than the similarly structured device using arylamine-based emitter. Single-organic layer device based on BITPI also shows superior performances, which are comparable to the best results from the arylamine-based donor-acceptor emitters, suggesting that PI is a stable donor with good hole transport/injection capability.
authors.affiliation: Center of Super-Diamond and Advanced Films (COSDAF) and Department of Biology and Chemistry, City University of Hong Kong , Hong Kong SAR, PR China.
authors.forename: Wen-Cheng
authors.initials: WC
authors.lastname: Chen
authors.affiliation: Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM) & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University , Suzhou 215123, PR China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Yuan
authors.affiliation: Department of Chemistry, Southern University of Science and Technology , Shenzhen 518055, PR China.
authors.forename: Shao-Fei
authors.initials: SF
authors.lastname: Ni
authors.affiliation: Center of Super-Diamond and Advanced Films (COSDAF) and Department of Biology and Chemistry, City University of Hong Kong , Hong Kong SAR, PR China.
authors.forename: Ze-Lin
authors.initials: ZL
authors.lastname: Zhu
authors.affiliation: Center of Super-Diamond and Advanced Films (COSDAF) and Department of Biology and Chemistry, City University of Hong Kong , Hong Kong SAR, PR China.
authors.forename: Jinfeng
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM) & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University , Suzhou 215123, PR China.
authors.forename: Zuo-Quan
authors.identifier: http://orcid.org/0000-0003-4447-2408
authors.initials: ZQ
authors.lastname: Jiang
authors.affiliation: Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM) & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University , Suzhou 215123, PR China.
authors.forename: Liang-Sheng
authors.identifier: http://orcid.org/0000-0002-2352-9666
authors.initials: LS
authors.lastname: Liao
authors.affiliation: Center of Super-Diamond and Advanced Films (COSDAF) and Department of Biology and Chemistry, City University of Hong Kong , Hong Kong SAR, PR China.
authors.forename: Fu-Lung
authors.initials: FL
authors.lastname: Wong
authors.affiliation: Center of Super-Diamond and Advanced Films (COSDAF) and Department of Biology and Chemistry, City University of Hong Kong , Hong Kong SAR, PR China.
authors.forename: Chun-Sing
authors.identifier: http://orcid.org/0000-0001-6557-453X
authors.initials: CS
authors.lastname: Lee
keywords: deep-blue OLED; donor−acceptor emitter; high efficiency; high stability; phenanthro[9,10-d]imidazole