Intramolecular Cyclization: A Convenient Strategy to Realize Efficient BT.2020 Blue Multi-Resonance Emitter for Organic Light-Emitting Diodes

Chen Cao; Ji-Hua Tan; Ze-Lin Zhu; Jiu-Dong Lin; Hong-Ji Tan; Huan Chen; Yi Yuan; Man-Kit Tse; Wen-Cheng Chen; Chun-Sing Lee

doi:10.1002/anie.202215226

Intramolecular Cyclization: A Convenient Strategy to Realize Efficient BT.2020 Blue Multi-Resonance Emitter for Organic Light-Emitting Diodes

Angew Chem Int Ed Engl. 2023 Mar 1;62(10):e202215226. doi: 10.1002/anie.202215226. Epub 2023 Jan 24.

Authors

Affiliations

¹ Center of Super-Diamond and Advanced Films (COSDAF) and Department of Chemistry, City University of Hong Kong, Hong Kong SAR, 999077, P. R. China.
² WISPO Advanced Materials (Suzhou) Co., Ltd., No. Building 12, 200 Xingpu Rd, SIP, Suzhou, P. R. China.
³ School of Chemistry and Chemical Engineering, University of South China, Hengyang, 421001, P. R. China.

PMID: 36593222
DOI: 10.1002/anie.202215226

Abstract

Rationally tuning the emission position and narrowing the full width at half-maximum (FWHM) of an emitter is of great importance for many applications. By synergistically improving rigidity, strengthening the resonant strength, inhibiting molecular bending and rocking, and destabilizing the HOMO energy level, a deep-blue emitter (CZ2CO) with a peak wavelength of 440 nm and an ultranarrow spectral FWHM of 16 nm (0.10 eV) was developed via intramolecular cyclization in a carbonyl/N resonant core (QAO). The dominant υ_0-0 transition character of CZ2CO gives a Commission Internationale de I'Éclairage coordinates (CIE) of (0.144, 0.042), nicely complying with the BT.2020 standard. Moreover, a hyper-fluorescent device based on CZ2CO shows a high maximum external quantum efficiency (EQE_max ) of 25.6 % and maintains an EQE of 22.4 % at a practical brightness of 1000 cd m^-2 .

Keywords: Aromatic Diketone; Blue Thermally Activated Delayed Fluorescence; Intramolecular Cyclization; Multi-Resonance Emitter; Organic Light-Emitting Diodes.