Non-halogenated solvent-processed highly efficient green Ir(iii) complexes with an external quantum efficiency exceeding 23% for phosphorescent organic light-emitting diodes. Issue 37 (2nd September 2020)

• Record Type: Journal Article
• Authors: Kumaresan, Raja; Maheshwaran, Athithan; Park, Ho-Yeol; Sung, Kyungmin; Choi, Jungmin; Cho, Woosum; Song, Myungkwan; Ahn, Sung Il; Jin, Sung-Ho
• Is Part Of: Journal of materials chemistry. Volume 8:Issue 37(2020)
• Page Start: 12959
• Page End: 12967
• Publication Date: 2020-09-02
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Optical materials -- Research -- Periodicals; Electronics -- Materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/d0tc02643c
• Languages: English
• ISSNs: 2050-7526

Abstract

Abstract : High efficiency green phosphorescent Ir(III ) complexes with solubilizing groups introduced to enable non-halogenated solvent-based fabrication of PHOLEDs with high EQE and CE values. Abstract : In the present study, three new highly efficient green emitting heteroleptic Ir(iii ) complexes based on 5 H -benzo[ c ][1, 5]naphthyridin-6-one derivatives were designed and synthesized for solution-processed PHOLEDs. The Ir(iii ) complex Ir1 consists of multifunctional 4-(2-ethoxyethoxy)picolinate as an ancillary ligand, whereas the Ir(iii ) complexes Ir2 and Ir3 contain conventional ancillary ligands, such as picolinate. Their corresponding photophysical, thermal and electrochemical properties were fully investigated. All three Ir(iii ) complexes exhibited intense green emission in solution at room temperature with high photoluminescence quantum yields (PLQYs). The optimized solution-processed green PHOLEDs exhibited a maximum external quantum efficiency (EQEmax ) of 24.56% with the maximum current efficiency (CEmax ) of 87.96 cd A −1 for Ir1 using a halogenated solvent, such as chlorobenzene for device fabrication. Additionally, we achieved a high EQEmax of 23.60% with CEmax of 85.22 cd A −1 for Ir1 using non-halogenated solvent, such as cyclohexanone for PHOLED fabrication. The Ir(iii ) complex, Ir1 showed a high electroluminescence brightness of 36 762 cd m −2 compared to Ir2 and Ir3 . To the best of our knowledge, the maximum EQE and CE of Ir1 is ranked the highest value among the Ir(iii ) complexes using a non-halogenated solvent for the fabrication of PHOLEDs to date.