Triplet-Triplet Annihilation Upconversion from Red to Blue Light Using a TADF Sensitizer Based Polymer

Area of Science:

• Organic chemistry
• Materials science
• Photophysics

Background:

• Thermally activated delayed fluorescence (TADF) molecules offer long triplet lifetimes and efficient intersystem crossing (ISC), making them promising for triplet-triplet annihilation upconversion (TTA-UC).
• TADF sensitizers can potentially replace traditional phosphorescent sensitizers in TTA-UC systems, enabling higher anti-Stokes shifts.

Purpose of the Study:

• To synthesize and characterize a novel polymer-based TTA-UC system utilizing a red-absorbing boron difluoride curcuminoid-based TADF molecule as the sensitizer.
• To investigate the upconversion properties, including anti-Stokes shift and photoluminescence quantum yield (PLQY), of the developed TTA-UC polymer.

Main Methods:

• Polymerization of a red-absorbing boron difluoride curcuminoid-based TADF molecule (sensitizer) with a 9,10-diphenylanthracene derivative (annihilator).
• Characterization of upconversion properties using power-dependent experiments and photoluminescence decay measurements.

Main Results:

• Successful synthesis of a polymer-based red-to-blue TTA-UC system.
• Achieved a significant anti-Stokes shift of up to 182 nm (0.9 eV).
• Obtained an upconversion photoluminescence quantum yield (PLQY) of 0.77%.

Conclusions:

• This work represents the first report of a TTA-UC polymer incorporating a TADF photosensitizer.
• Demonstrates the effectiveness of TADF sensitizers in enhancing anti-Stokes shifts within TTA-UC systems.
• Highlights the feasibility of constructing polymer-based upconversion systems, expanding applications for purely organic TTA-UC.