Rapid room temperature synthesis of red iridium(iii) complexes containing a four-membered Ir-S-C-S chelating ring for highly efficient OLEDs with EQE over 30

Guang-Zhao Lu; Ning Su; Hui-Qing Yang; Qi Zhu; Wen-Wei Zhang; You-Xuan Zheng; Liang Zhou; Jing-Lin Zuo; Zhao-Xu Chen; Hong-Jie Zhang

doi:10.1039/c8sc05605f

Rapid room temperature synthesis of red iridium(iii) complexes containing a four-membered Ir-S-C-S chelating ring for highly efficient OLEDs with EQE over 30

Chem Sci. 2019 Feb 11;10(12):3535-3542. doi: 10.1039/c8sc05605f. eCollection 2019 Mar 28.

Authors

Affiliations

¹ State Key Laboratory of Coordination Chemistry , Jiangsu Key Laboratory of Advanced Organic Materials , Collaborative Innovation Center of Advanced Microstructures , School of Chemistry and Chemical Engineering , Nanjing University , Nanjing 210093 , P. R. China . Email: yxzheng@nju.edu.cn ; Email: zuojl@nju.edu.cn ; Email: zxchen@nju.edu.cn.
² State Key Laboratory of Rare Earth Resource Utilization , Changchun Institute of Applied Chemistry , Chinese Academy of Sciences , Changchun 130022 , P. R. China . Email: zhoul@ciac.ac.cn.

Abstract

Three red cyclometalated iridium(iii) complexes (4tfmpq)₂Ir(dipdtc), (4tfmpq)₂Ir(dpdtc) and (4tfmpq)₂Ir(Czdtc) (4tfmpq = 4-(4-(trifluoromethyl)phenyl)quinazoline, dipdtc = N,N-diisopropyl dithiocarbamate, dpdtc = N,N-diphenyl dithiocarbamate, and Czdtc = N-carbazolyl dithiocarbamate) containing the unique four-membered Ir-S-C-S backbone ring were synthesized in five minutes at room temperature with good yields, and the Gibbs free energy calculation results indicate that all reactions are exothermic and thermodynamically favorable processes. The emission colors (λ _peak = 641-611 nm), photoluminescence quantum efficiencies (Φ _P = 58.3-93.0%) and bipolar properties can be effectively regulated by introducing different electron-donating substituents into the dithiocarbamate ancillary ligands. Employing these emitters, organic light emitting diodes (OLEDs) with double emissive layers exhibit excellent performances with a maximum brightness over 60 000 cd m^-2, a maximum current efficiency of 40.68 cd A^-1, a maximum external quantum efficiency (EQE_max) of 30.54%, and an EQE of 26.79% at the practical luminance of 1000 cd m^-2. These results demonstrate that Ir(iii) complexes with sulfur-containing ligands can be rapidly synthesized at room temperature, which is key to the production of metal luminescent materials for large-scale application in highly efficient OLEDs.