title: Highly Efficient Near-Infrared Delayed Fluorescence Organic Light Emitting Diodes Using a Phenanthrene-Based Charge-Transfer Compound.
abstract: Significant efforts have been made to develop high-efficiency organic light-emitting diodes (OLEDs) employing thermally activated delayed fluorescence (TADF) emitters with blue, green, yellow, and orange-red colors. However, efficient TADF materials with colors ranging from red, to deep-red, to near-infrared (NIR) have been rarely reported owing to the difficulty in molecular design. Herein, we report the first NIR TADF molecule TPA-DCPP (TPA=triphenylamine; DCPP=2,3-dicyanopyrazino phenanthrene) which has a small singlet-triplet splitting (ΔEST ) of 0.13 eV. Its nondoped OLED device exhibits a maximum external quantum efficiency (EQE) of 2.1 % with a Commission International de L'Éclairage (CIE) coordinate of (0.70, 0.29). Moreover, an extremely high EQE of nearly 10 % with an emission band at λ=668 nm has been achieved in the doped device, which is comparable to the most-efficient deep-red/NIR phosphorescent OLEDs with similar electroluminescent spectra.
authors.affiliation: State Key Lab of Supramolecular Structure and Materials, College of Chemistry, Jilin University, 2699 Qianjin Avenue, Changchun, 130012 (P.R. China).
authors.forename: Shipan
authors.initials: S
authors.lastname: Wang
authors.affiliation: State Key Lab of Supramolecular Structure and Materials, College of Chemistry, Jilin University, 2699 Qianjin Avenue, Changchun, 130012 (P.R. China).
authors.forename: Xianju
authors.initials: X
authors.lastname: Yan
authors.affiliation: State Key Lab of Supramolecular Structure and Materials, College of Chemistry, Jilin University, 2699 Qianjin Avenue, Changchun, 130012 (P.R. China).
authors.forename: Zong
authors.initials: Z
authors.lastname: Cheng
authors.affiliation: State Key Lab of Supramolecular Structure and Materials, College of Chemistry, Jilin University, 2699 Qianjin Avenue, Changchun, 130012 (P.R. China).
authors.forename: Hongyu
authors.initials: H
authors.lastname: Zhang
authors.affiliation: State Key Lab of Supramolecular Structure and Materials, College of Chemistry, Jilin University, 2699 Qianjin Avenue, Changchun, 130012 (P.R. China).
authors.forename: Yu
authors.initials: Y
authors.lastname: Liu
authors.affiliation: State Key Lab of Supramolecular Structure and Materials, College of Chemistry, Jilin University, 2699 Qianjin Avenue, Changchun, 130012 (P.R. China). yuewang@jlu.edu.cn.
authors.forename: Yue
authors.initials: Y
authors.lastname: Wang
keywords: charge transfer; delayed fluorescence; near-infrared luminescence; organic light-emitting diodes; photophysics