Inkjet Printing of High-Color-Purity Blue Organic Light-Emitting Diodes with Host-Free Inks

Area of Science:

• Materials Science
• Organic Electronics
• Display Technology

Background:

• Inkjet printing offers mask-free patterning for active matrix displays.
• Thermally activated delayed fluorescence (TADF) emitters enable efficient, heavy-metal-free light emission.
• Multi-resonance TADF molecules with narrow spectral width are crucial for wide color-gamut displays.

Purpose of the Study:

• To develop host-free TADF inks suitable for inkjet printing.
• To demonstrate the feasibility of printing OLEDs using these inks on a seeding layer.
• To enhance the efficiency and spectral properties of inkjet-printed OLEDs.

Main Methods:

• Development of host-free TADF inks at a low concentration (1 mg/mL).
• Inkjet printing of TADF inks onto a combined seeding and hole-transporting layer.
• Characterization of the inkjet-printed organic light-emitting diodes (OLEDs).

Main Results:

• Achieved a maximum external quantum efficiency of 13.1% in the inkjet-printed OLED, a 21.8-fold improvement.
• Demonstrated a remarkably narrow full width at half maxima (FWHM) of 32 nm.
• Facilitated highly efficient energy transfer through effective sensitizer dispersion.

Conclusions:

• Proof-of-concept for host-free TADF inks printed on a mixed seeding layer.
• Inkjet printing is a viable method for fabricating efficient, narrow-spectrum OLEDs.
• The developed inks and printing process are suitable for wide color-gamut display applications.