Towards Printed Organic Light-Emitting Devices: A Solution-Stable, Highly Soluble Cu^I -NHetPHOS

Area of Science:

• Materials Science
• Organic Electronics
• Photochemistry

Background:

• Efficient organic light-emitting diodes (OLEDs) are crucial for display technology.
• Current progress in OLEDs is limited by iridium-free emitters with low solubility and chemical instability.
• Thermally activated delayed fluorescence (TADF) emitters offer a pathway to high efficiency without heavy metals.

Purpose of the Study:

• To develop a novel, iridium-free TADF emitter with enhanced solubility and chemical stability.
• To demonstrate the suitability of the new emitter for printing techniques and ambient condition processing.
• To fabricate and characterize a TADF-based OLED device utilizing the developed emitter.

Main Methods:

• Synthesis and characterization of a novel copper(I)-based TADF emitter.
• Solubility testing in relevant printing solvents, achieving up to 100 g/L.
• Chemical stability assessment using X-ray absorption spectroscopy and other techniques.
• Fabrication of OLED devices and measurement of optoelectronic properties, including external quantum efficiency (EQE).

Main Results:

• A highly soluble (100 g/L) and chemically stable Cu(I)-based TADF emitter was successfully synthesized.
• The emitter's integrity and optoelectronic properties were maintained during solution processing, even under ambient conditions.
• A TADF-based OLED device achieved a notable 11±2% external quantum efficiency (EQE).

Conclusions:

• The developed copper-based TADF emitter overcomes the limitations of solubility and stability in current materials.
• This advancement facilitates the mass production of OLEDs using cost-effective printing techniques.
• The demonstrated device efficiency highlights the potential of this new material for next-generation displays.