Highly reliable benzothiophene-phenylquinoline based heteroleptic Ir(III) complexes; The solution process NIR phosphorescence organic light-emitting diodes

ABSTRACT

In this work, a canny combination of thiophe-phenylquinoline based red emitting heteroleptic Ir(III) complexes have been synthesized and used for solution processed phosphorescent organic light-emitting diode applications (PhOLEDs). The thermal stabilities, photophysical properties, electrochemical behaviors and electroluminescence properties are systematically investigated. An easy synthetic pathway is followed for preparing heteroleptic bis(2-(benzothiophen-2-yl)-4-phenylquinoline)iridium picolinicacid (BTPQ)₂Ir(pic) and bis(2-(benzothiophen-2-yl)-4-phenylquinoline)iridium acetylacetate (BTPQ)₂Ir(acac) complexes. The NIR PhOLEDs were fabricated with the configuration of ITO/PEDOT:PSS (40 nm)/TCTA:TPBI:Ir(III) complexes (40 nm)/TmPyPB (20 nm)/LiF (1 nm)/Al (100 nm). The optimized red PhOLEDs showed maximum external quantum efficiency of 11.23% with stable NIR CIE coordinates (0.706, 0.277).

KEYWORDS:

• Benzothiophene
• iridium(III) complex
• near-infrared
• phenylquinoline
• red PhOLEDs
• solution process

Funding

This work was supported by the Pioneer Research Center Program through the National Research Foundation of Korea funded by the Ministry of Science, ICT & Future Planning (MSIP) of Korea (NRF-2013M3C1A3065522).