Highly efficient iridium(III) phosphors with phenoxy-substituted ligands and their high-performance OLEDs

Guiping Tan; Shuming Chen; Ning Sun; Yanhu Li; Daniel Fortin; Wai-Yeung Wong; Hoi-Sing Kwok; Dongge Ma; Hongbin Wu; Lixiang Wang; Pierre D. Harvey

doi:10.1039/C2TC00123C

Highly efficient iridium(iii) phosphors with phenoxy-substituted ligands and their high-performance OLEDs†

Guiping Tan,^ab Shuming Chen,^c Ning Sun,^d Yanhu Li,^e Daniel Fortin,^f Wai-Yeung Wong,*^b Hoi-Sing Kwok,*^c Dongge Ma,*^d Hongbin Wu,*^e Lixiang Wang^d and Pierre D. Harvey*^f

Author affiliations

* Corresponding authors

^a College of Chemistry and Environmental Engineering, Dongguan University of Technology, Dongguan 523808, P.R. China

^b Institute of Molecular Functional Materials, Department of Chemistry, Institute of Advanced Materials, Hong Kong Baptist University, Waterloo Road, Kowloon Tong, Hong Kong, P.R. China
E-mail: rwywong@hkbu.edu.hk
Fax: +852-3411-7348
Tel: +852-3411-7074

^c Centre for Display Research and Department of Electronic and Computer Engineering, The Hong Kong University of Science & Technology, Clear Water Bay, Kowloon, Hong Kong, P.R. China
E-mail: eekwok@ust.hk

^d State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P.R. China
E-mail: mdg1014@ciac.jl.cn

^e Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640, P.R. China
E-mail: hbwu@scut.edu.cn

^f Départment de Chimie, Université de Sherbrooke, 2550 Boul. Université, Sherbrooke, PQ, J1K 2R1 Canada
E-mail: Pierre.Harvey@USherbrooke.ca

Abstract

Two new iridium(III) cyclometallated complexes (1 and 2) based on the 2-(1-phenoxy-4-phenyl)-5-methylpyridine ligand have been developed. By attaching a flexible phenoxy group on the phenyl ring of 2-phenylpyridine (Hppy), the light-emitting properties of the resulting Ir^III complexes have been improved, while the introduction of an electron-donating methyl group on the pyridyl ring of Hppy can keep the triplet emission in the green region by compensating for the reduced energy gap caused by the phenoxy group. Owing to the unique electronic structures induced by the ligand, the vacuum-evaporated organic light-emitting devices (OLEDs) of the type [ITO/NPB (40 nm)/(1 or 2):CBP (20 nm)/BCP (10 nm)/Alq₃ (30 nm)/LiF (1 nm)/Al (100 nm)] furnished peak OLED efficiencies at 10.0%, 31.1 cd A⁻¹ and 14.5 lm W⁻¹ for 1 and 11.7%, 38.1 cd A⁻¹ and 31.8 lm W⁻¹ for 2. By replacing the electron-injection/electron-transporting materials (BCP and Alq₃) with TPBi, the green-emitting devices based on 1 gave outstanding peak efficiencies at 22.5%, 76.2 cd A⁻¹ and 72.8 lm W⁻¹. Extremely high peak efficiencies of 24.5%, 84.6 cd A⁻¹ and 77.6 lm W⁻¹ were even obtained for the 2-doped devices and both of them are superior in performance to the benchmark dopants Ir(ppy)₃ and Ir(ppy)₂(acac). Moreover, polymer light-emitting devices were also fabricated using 1 and 2via the spin-coating method, and their device performances are characterized by 14.4%, 39.5 cd A⁻¹ and 12.4 lm W⁻¹ for 1 and 12.6%, 29.6 cd A⁻¹ and 18.1 lm W⁻¹ for 2. When 2 was used to make three-color white-light OLEDs, respectable device efficiencies of 15.3 cd A⁻¹, 7.5% and 9.1 lm W⁻¹ were achieved and their white color CIE coordinates are improved relative to Ir(ppy)₃.

Journal of Materials Chemistry C

Highly efficient iridium(iii) phosphors with phenoxy-substituted ligands and their high-performance OLEDs†

Abstract

Supplementary files

Article information

Download Citation

Permissions

Highly efficient iridium(III) phosphors with phenoxy-substituted ligands and their high-performance OLEDs

Social activity

Search articles by author

Spotlight

Advertisements