Blue-to-Green Fine-Tunable Narrowband Delayed Fluorescence in Peripherally Dendritic Modified Bis-Indolocarbazoles

Area of Science:

• Materials Science
• Organic Electronics
• Photophysics

Background:

• Highly efficient narrowband organic luminophores are crucial for achieving high color purity in organic light-emitting diodes (OLEDs).
• Controlling structural relaxation and vibronic couplings is key to achieving desired narrowband emissions.

Purpose of the Study:

• To demonstrate exquisite color tuning of narrowband emissions from deep blue to green using dendritic modifications in non-boron molecular systems.
• To develop novel organic luminophores based on the indolo[3,2,1-jk]indolo[1',2',3':1,7]indolo[3,2-b]carbazole (BICz) core.

Main Methods:

• Synthesized BICz derivatives (BICz-1.5G, BICz-2G, BICz-2GII) by attaching arylamine-based dendritic units to the BICz core.
• Conducted comprehensive photophysical and computational studies to analyze emission properties.
• Fabricated OLED devices incorporating the developed luminophores.

Main Results:

• Achieved tunable narrowband emissions from deep blue to green with high color purity.
• BICz derivatives exhibited enhanced thermally activated delayed fluorescence (TADF) properties.
• OLEDs demonstrated high external quantum efficiencies (up to 28.5%) and excellent color coordinates (e.g., (0.13, 0.10) for blue, (0.21, 0.68) for green).

Conclusions:

• Dendritic modifications enable precise color tuning of narrowband emissions without compromising emission ability.
• The developed organic luminophores show significant potential for high-performance, high-color-purity OLED applications.
• Findings expand the molecular design strategies for narrowband organic luminophores.