title: Highly Efficient Long-Wavelength Thermally Activated Delayed Fluorescence OLEDs Based on Dicyanopyrazino Phenanthrene Derivatives.
abstract: Highly efficient long-wavelength thermally activated delayed fluorescence (TADF) materials are developed using 2,3-dicyanopyrazino phenanthrene (DCPP) as the electron acceptor (A), and carbazole (Cz), diphenylamine (DPA), or 9,9-dimethyl-9,10-dihydroacridine (DMAC) as the electron donor (D). Because of the large, rigid π-conjugated structure and strong electron-withdrawing capability of DCPP, TADF molecules with emitting colors ranging from yellow to deep-red are realized with different electron-donating groups and π-conjugation length. The connecting modes between donor and acceptor, that is, with or without the phenyl ring as π-bridge, are also investigated to study the π-bridge effect on the thermal, photophysical, electrochemical, and electroluminescent properties. Yellow, orange, red, and deep-red organic light-emitting diodes (OLEDs) based on DCPP derivatives exhibit high efficiencies of 47.6 cd A-1(14.8%), 34.5 cd A-1(16.9%), 12.8 cd A-1(10.1%), and 13.2 cd A-1(15.1%), with Commission Internationale de L'Eclairage (CIE) coordinates of (0.44, 0.54), (0.53, 0.46), (0.60, 0.40), and (0.64, 0.36), respectively, which are among the best values for long-wavelength TADF OLEDs.
authors.affiliation: State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, People's Republic of China.
authors.forename: Shipan
authors.initials: S
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, People's Republic of China.
authors.forename: Zong
authors.initials: Z
authors.lastname: Cheng
authors.affiliation: State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, People's Republic of China.
authors.forename: Xiaoxian
authors.initials: X
authors.lastname: Song
authors.affiliation: State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, People's Republic of China.
authors.forename: Xianju
authors.initials: X
authors.lastname: Yan
authors.affiliation: State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, People's Republic of China.
authors.forename: Kaiqi
authors.initials: K
authors.lastname: Ye
authors.affiliation: State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, People's Republic of China.
authors.forename: Yu
authors.identifier: http://orcid.org/0000-0001-8686-1503
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Centre for Advanced Optoelectronic Functional Materials Research and Key Laboratory for UV Light-Emitting Materials and Technology of Ministry of Education, Northeast Normal University , Changchun 130024, People's Republic of China.
authors.forename: Guochun
authors.initials: G
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, People's Republic of China.
authors.forename: Yue
authors.identifier: http://orcid.org/0000-0001-6936-5081
authors.initials: Y
authors.lastname: Wang
keywords: dicyanopyrazino phenanthrene derivatives; intramolecular charge transfer excited states; long-wavelength emitters; organic light-emitting diodes; thermally activated delayed fluorescence