Thermally activated delayed fluorescence exciplexes with phosphor components realizing deep-red to near-infrared electroluminescence

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Materials for optical and electronic devices, 2022-10, Vol.1 (41), p.15593-156
• Main Authors: Zhang, Ming, Zheng, Cai-Jun, Zhang, Heng-Yuan, Yang, Hao-Yu, Wang, Kai, Shi, Yi-Zhong, Lin, Hui, Tao, Si-Lu, Zhang, Xiao-Hong
• Format: Article
• Language: English
• Subjects: Chemical synthesis; Electroluminescence; Emission; Emitters; Excitons; Fluorescence; Heavy metals; Near infrared radiation; Phosphors; Spin-orbit interactions
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/d2tc02694e

Compared with single-molecule thermally activated delayed fluorescence emitters, exciplexes can simplify the complicated molecule design and synthesis and have the superiority of conveniently realizing spectra with a bathochromic shift via mixing donor and acceptor components. In this work, we develop a series of novel exciplexes with phosphor components showing emission in the range of deep-red to near-infrared (NIR). The phosphor-incorporated exciplexes would improve the utilization of triplet excitons due to the spin-orbit coupling (SOC) effect of heavy metal atoms in phosphors. By employing B2PyMPM, B3PyMPM and B4PyMPM as acceptors, three exciplexes were first constructed with phosphor Ir-817. Optimized B2PyMPM:Ir-817, B3PyMPM:Ir-817 and B4PyMPM:Ir-817-based OLEDs show electroluminescence (EL) peaks at 612, 640 and 672 nm and maximum external quantum efficiencies (EQE) of 3.1%, 1.45% and 1.03%, respectively. To further develop exciplexes with NIR emission, TRZ-1SO 2 , TRZ-2SO 2 and TRZ-3SO 2 with stronger electron-withdrawing abilities were chosen as the acceptors. Notably, the TRZ-3SO 2 :Ir-817-based device exhibits an EL peak at 746 nm and a maximum EQE of 0.20%. These results demonstrate the potential and feasibility of using phosphor-incorporated exciplexes in the development of NIR exciplexes. Compared with single-molecule TADF emitters, exciplexes can simplify the complicated molecule design and synthesis and have the superiority of conveniently realizing spectra with a bathochromic shift via mixing donor and acceptor components.