Intermolecular Interaction-Induced Thermally Activated Delayed Fluorescence Based on a Thiochromone Derivative

Area of Science:

• Materials Science
• Organic Electronics
• Photophysics

Background:

• Achieving high exciton utilization efficiency in organic light-emitting diodes (OLEDs) is crucial for device performance.
• Thermally activated delayed fluorescence (TADF) is a promising mechanism for high efficiency, but external modulation methods are sought.
• Molecular design and aggregation state significantly influence TADF properties.

Purpose of the Study:

• To explore extrinsic methods for modulating TADF properties.
• To investigate a new thiochromone derivative (THI-PhCz) for tunable TADF.
• To understand the role of intermolecular interactions on TADF in different states.

Main Methods:

• Synthesis and characterization of a novel thiochromone derivative (THI-PhCz).
• Investigation of THI-PhCz's photophysical properties in crystalline and amorphous states.
• Fabrication and analysis of THI-PhCz doped in various host materials for OLED applications.

Main Results:

• THI-PhCz exhibits tunable TADF properties dependent on molecular packing and aggregation state.
• Host-dependent TADF was observed in amorphous films, attributed to host-guest intermolecular interactions affecting the 3CT state.
• A short delay lifetime of 108 ns was measured, indicating efficient TADF.

Conclusions:

• Intermolecular interactions in crystals and amorphous films can be tuned to generate TADF, offering an alternative to solely molecular design.
• This approach provides a new perspective for developing efficient OLEDs with reduced efficiency roll-off.
• The findings contribute to achieving effective exciton utilization in organic electronic devices.