Ultrabright Pdots with a Large Absorbance Cross Section and High Quantum Yield.

Area of Science:

• Materials Science
• Nanotechnology
• Biomedical Engineering

Background:

• Semiconducting polymer dots (Pdots) offer high single-particle brightness due to large absorption cross sections (σ).
• Aggregation-induced self-quenching limits Pdot quantum yield (Φ) to below 40%.
• Förster Resonance Energy Transfer (FRET) is explored to reduce self-quenching but yields low Φ values.

Purpose of the Study:

• To develop an approach for achieving ultrabright FRET-based Pdots with simultaneously high σ and Φ.
• To investigate the impact of self-quenching and optimize FRET conditions for enhanced Pdot performance.

Main Methods:

• Investigated the effect of nonabsorbing polyphenyl addition on poly(9,9-dioctylfluorene) (PFO) Pdot Φ.
• Optimized FRET-based Pdot brightness by varying donor/acceptor polymer combinations (PFO, PFP, PFPV, PFBT) and ratios.
• Utilized poly(styrene-co-maleic anhydride) as a surfactant polymer.

Main Results:

• Adding 30 mol % polyphenyl to PFO Pdots increased Φ from 13.4% to 71.2%, demonstrating reduced self-quenching.
• Achieved ultrabright blue-emitting Pdots (Φ 73.1%, σR 97.5%) using PFP/PFPV at 2.5 mol % acceptor.
• Developed ultrabright green (Φ 76.0%) and red (Φ 64.2%) emitting Pdots through optimized FRET and cascade FRET strategies.

Conclusions:

• The developed approach yields ultrabright Pdots across the visible spectrum with high Φ and σ.
• Optimizing D/A spectral overlap and using minimal FRET acceptors are key to maximizing Pdot brightness.
• These ultrabright Pdots show significant potential for advanced biomedical imaging and sensing applications.