Thermochromic aggregation-induced dual phosphorescence via temperature-dependent sp³-linked donor-acceptor electronic...

Area of Science:

• Materials Science
• Organic Chemistry
• Photophysics

Background:

• Aggregation-induced emission (AIE) overcomes luminescence quenching in solid states.
• Room temperature phosphorescence (RTP) is crucial for advanced optical applications.
• Designing molecules with controlled excited-state dynamics remains a challenge.

Purpose of the Study:

• To synthesize and characterize novel triphenylamine (TPA)-based luminophores.
• To investigate the aggregation-induced emission (AIE) and room temperature phosphorescence (RTP) properties.
• To explore the influence of molecular structure on excited-state dynamics and phosphorescence behavior.

Main Methods:

• Synthesis of six TPA-based molecules with an sp³ linker connecting donor and acceptor units.
• Photoluminescence spectroscopy to study emission properties at different temperatures.
• Theoretical calculations (e.g., DFT) to understand electronic structure and excited states.

Main Results:

• Six TPA-based AIE-active RTP luminophores were successfully synthesized.
• Distinct dual phosphorescence bands observed at low temperatures, originating from localized donor and acceptor triplet states.
• A single, merged RTP band observed at room temperature, indicating temperature-dependent excited-state dynamics.

Conclusions:

• The TPA-based molecular construct acts as an intermediate between fully conjugated and mixed donor-acceptor systems.
• Temperature-dependent phosphorescence arises from minima on the lowest triplet excited state (T₁).
• Findings offer insights into designing high-freedom molecular systems with complex photophysical properties.