Molecular Orientation-Directed Isomerization in Indolocarbazole-Embedded Multiple Resonance Emitter Enables...

Area of Science:

• Materials Science
• Organic Electronics
• Photophysics

Background:

• Multiple resonance thermally activated delayed fluorescence (MR-TADF) emitters are key for high-definition displays.
• Achieving high efficiency, narrowband, and pure-green emission simultaneously is a significant challenge in MR-TADF technology.

Purpose of the Study:

• To design and synthesize novel MR-TADF emitters with pure-green emission.
• To explore an orientation-directed isomerization strategy for constructing dual-boron-containing architectures.
• To establish a molecular engineering principle for efficient, narrowband, pure-green MR-TADF emitters.

Main Methods:

• Utilized an orientation-directed isomerization strategy on an indolocarbazole (ICz) building block.
• Constructed a syn-oriented para-N-π-N dual-boron-containing architecture.
• Synthesized and characterized the proof-of-concept emitter DBN-cpICz.

Main Results:

• DBN-cpICz exhibits pure-green photoluminescence (520 nm, FWHM 20 nm).
• Organic light-emitting diodes using DBN-cpICz achieve pure-green electroluminescence (522 nm, FWHM 24 nm) with 36.4% external quantum efficiency.
• The emitter surpasses NTSC green requirements and approaches BT.2020 standards.

Conclusions:

• The designed para-N-π-N dual-boron ICz architecture balances intramolecular charge transfer (ICT) and short-range charge transfer (SRCT) for narrowband emission.
• The study provides a robust molecular engineering principle for developing efficient, narrowband, pure-green MR-TADF emitters.
• This work advances the development of next-generation display technologies.