Pentagonal/Heptagonal-Lock Strategy Enables Narrowband Red Multiple Resonance Emitters Through Temperature-Controlled...

Area of Science:

• Organic Chemistry
• Materials Science
• Photophysics

Background:

• π-extension is key for red-shifted emission in multiple resonance (MR) emitters.
• However, π-extension often causes spectral broadening, hindering high-performance red MR material development.

Purpose of the Study:

• To develop a novel π-extension strategy for red-shifted emission with narrow bandwidth.
• To enable broad color tuning by adjusting molecular orbital energy gaps.

Main Methods:

• A naphthalene-based pentagonal/heptagonal-lock π-extension strategy was employed.
• Precise π-extension was achieved via controlled Scholl reactions at varying temperatures, forming sequential pentagonal and heptagonal rings.

Main Results:

• A significant redshift of 116 nm was achieved while maintaining a narrow emission bandwidth.
• A red fluorescent emitter with a 600 nm emission peak and 30 nm full-width-at-half-maximum was obtained.
• Organic light-emitting diode (OLED) devices demonstrated a high external quantum efficiency of 21.3% with minimal efficiency roll-off.

Conclusions:

• The developed π-extension strategy effectively achieves red-shifted emission with narrow bandwidths.
• This approach facilitates color tuning and leads to high-performance red OLEDs.
• The method offers a promising route for designing advanced organic electronic materials.