Minimum effort, maximum effect: modulating twisted intramolecular charge transfer for ultralong room temperature...

Area of Science:

• Materials Science
• Organic Chemistry
• Photophysics

Background:

• Efficient organic ultralong room temperature phosphorescence (OURTP) requires effective population and stabilization of triplet excitons.
• Existing strategies often involve complex molecular designs or external stimuli.
• Understanding the fundamental mechanisms governing triplet state dynamics is crucial for material design.

Purpose of the Study:

• To develop a facile strategy for achieving efficient OURTP using minimalist molecular systems.
• To investigate the role of the twisted intramolecular charge-transfer (TICT) process in modulating photophysical properties.
• To establish a direct structure-property relationship between TICT characteristics and OURTP performance.

Main Methods:

• Design and synthesis of minimalist single-benzene luminophores (SBLs) with modulated TICT processes.
• Synergistic attenuation of steric hindrance in electron-donating groups and electron-withdrawing groups to facilitate TICT.
• Utilizing a polyvinyl alcohol (PVA) matrix to create a rigid hydrogen-bonding network for triplet state stabilization.

Main Results:

• Demonstrated a 'minimum effort, maximum effect' approach by precisely controlling TICT formation in SBLs.
• Achieved efficient narrowing of the singlet-triplet energy gap (ΔE_ST) and enhanced spin-orbit coupling (SOC) via TICT.
• Observed significant enhancement in triplet population and stabilization, leading to high-performance OURTP.

Conclusions:

• Established a direct correlation between TICT character and OURTP performance, highlighting a molecular-level 'butterfly effect'.
• Showcased a novel paradigm for designing high-performance OURTP materials from simple and compact molecular architectures.
• The findings provide a new pathway for developing advanced phosphorescent materials for various applications.