Near-infrared cyclometalated iridium(iii) complexes with bipolar features for efficient OLEDs via solution-processing

Area of Science:

• Materials Science
• Organic Chemistry
• Photophysics

Background:

• Organic light-emitting diodes (OLEDs) require efficient charge transport materials.
• Iridium(III) complexes are widely studied for their photoluminescent properties.

Purpose of the Study:

• To design and synthesize a novel bipolar near-infrared (NIR) iridium(III) complex.
• To investigate the impact of incorporating hole transporting (HT) and electron transporting (ET) groups on optophysical and electroluminescence performance.

Main Methods:

• Synthesis of a novel bipolar iridium(III) complex, (CH3OTPA-BTz-Iq)2Ir(pic-OXD).
• Fabrication and characterization of OLED devices using the synthesized complex and a parent complex.
• Evaluation of optophysical properties and electroluminescence performance, including external quantum efficiency (EQE).

Main Results:

• The novel complex (CH3OTPA-BTz-Iq)2Ir(pic-OXD) exhibits improved optophysical and electroluminescence properties compared to the parent complex (CH3OTPA-BTz-Iq)2Irpic.
• OLEDs based on (CH3OTPA-BTz-Iq)2Ir(pic-OXD) achieved a maximum external quantum efficiency (EQEmax) of 1.15% at 716 nm.
• This represents a significant improvement over the parent complex-based OLEDs, which showed an EQEmax of 0.41% at 723 nm.

Conclusions:

• Incorporating both triphenylamine (TPA) and oxadiazole (OXD) groups into the iridium(III) complex ligand enhances performance.
• The designed bipolar NIR iridium(III) complex is a promising material for efficient OLED applications.