Thermal switches between delayed fluorescence and persistent phosphorescence based on a keto-BODIPY electron acceptor

Area of Science:

• Organic Chemistry
• Materials Science
• Photophysics

Background:

• Donor-acceptor molecular materials are crucial for optoelectronics.
• Carbazole and keto-BODIPY are established components in functional materials.
• Tuning electronic properties through molecular design is key for advanced applications.

Purpose of the Study:

• To synthesize and characterize new twisted donor-acceptor molecular materials.
• To investigate the photophysical properties, including delayed fluorescence and phosphorescence.
• To understand the structure-property relationships governing their optical behavior.

Main Methods:

• Synthesis of carbazole-keto-BODIPY derivatives (3a and 3b).
• Spectroscopic analysis (absorption, emission, time-resolved).
• X-ray diffraction and theoretical calculations.

Main Results:

• Successful preparation of twisted donor-acceptor molecules 3a and 3b.
• Observation of strong intramolecular charge transfer (ICT) character.
• Efficient delayed fluorescence (μs lifetimes) and persistent phosphorescence (ms lifetimes at 77 K).
• Emission color tuning from blue to yellow/red via chemical modification.

Conclusions:

• The synthesized materials exhibit unique photophysical properties, including efficient delayed fluorescence and phosphorescence.
• Hybridized local and charge-transfer (HLCT) states and enhanced spin-orbital coupling (SOC) are responsible for the observed phenomena.
• These findings provide insights into designing advanced molecular materials for optoelectronic devices.