Anion-π interaction guided switchable TADF and low-temperature phosphorescence in phosphonium salts for multiplexed...

Area of Science:

• Organic Chemistry
• Materials Science
• Photophysics

Background:

• Anion-π+ interactions are crucial in organic aggregates, influencing emission properties.
• Phosphonium salts are explored for their luminescent potential.

Purpose of the Study:

• To introduce and investigate anion-π+ interactions in phosphonium salts.
• To achieve tunable thermally activated delayed fluorescence and phosphorescence.
• To explore the impact of anion variations on luminescence.

Main Methods:

• Synthesis of phosphonium salts with varying counter anions (BF4-, CF3SO3-, PF6-, NO3-, I-).
• Spectroscopic analysis to study emission spectra and decay times.
• Photoluminescence quantum yield measurements.

Main Results:

• Tunable emission from deep-blue to yellow achieved by modifying anion-π+ interaction strength.
• Luminescent decay times adjustable from milliseconds to seconds.
• Near 100% photoluminescence quantum yield for blue emission with specific anions.
• Suppression of π-π stacking leading to ultra-high photoluminescence yields.
• Solvation effects causing bathochromic shifts in solid-state phosphonium iodide.

Conclusions:

• Anion-π+ interactions provide a powerful tool for tuning luminescence in phosphonium salts.
• The findings offer new insights into the design of advanced luminescent materials.
• This work highlights the potential of phosphonium aggregates for optoelectronic applications.