Density functional theory and time-dependent density functional study a series of iridium complexes with low-efficiency roll-off properties

ABSTRACT

A series of blue phosphorescent heteroleptic cyclometalated Ir(III) complexes with mesitylphenyl-imidazole ligands for organic light-emitting devices have been theoretically studied. We want to find their electronic structures, spectroscopic properties, and application value for organic light-emitting devices. (fppz)₂Ir(acac), (fppz)₂Ir(tpip), (dfbdp)₂Ir(fppz), (F-fppz)₂Ir(acac), (F-fppz)₂Ir(tpip), and (dfbdp)₂Ir(F-fppz) are investigated with DFT and TD-DFT approaches, where, for (fppz)₂Ir(acac), (fppz denotes 2-(5-(trifluoromethyl)-4H-pyrazol-3-yl)pyridine, and acac denotes acetylacetonate); for (fppz)₂Ir(tpip), tpip denotes tetraphenylimido-diphosphinate; and, for (F-fppz)₂Ir(acac) and (F-fppz)₂Ir(tpip), F-fppz denotes 2-(5-fluoro-4H-pyrazol-3-yl)pyridine.

GRAPHICAL ABSTRACT

KEYWORDS:

• Efficiency roll-off
• Ir(III) complexes
• OLEDs
• DFT
• TD-DFT

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors are grateful for financial support from the National Natural Science Foundation for Creative Research Group [grant numbers 21701047 and 11947039], the Science and Technology Development of Jilin Province of China [grant number 20180520191JH and 20180520199JH], the Thirteenth Five-Year Program for Science and Technology of the Education Department of Jilin Province [grant number JJKH20191024KJ and JJKH20180762KJ].