Organic Phosphorescence Lasing Based on a Thermally Activated Delayed Fluorescence Emitter

Area of Science:

• Organic electronics
• Photonic materials

Background:

• Organic phosphorescence materials offer potential for triplet-based lasing but face challenges with low quantum efficiency and optical loss.
• Thermally activated delayed fluorescence (TADF) emitters show promise for optical gain via reverse intersystem crossing (RISC).

Purpose of the Study:

• To design a multifunctional organic gain material that combines TADF and phosphorescence properties for efficient lasing.
• To achieve high optical gain and efficient triplet utilization in a single material.

Main Methods:

• Designed a novel organic molecule incorporating oxygen substitutions to enhance spin-flip and delayed fluorescence.
• Fabricated single-crystalline nanowires of H-aggregates to lower triplet energy levels.
• Investigated amplified spontaneous emission (ASE) in solution and phosphorescence lasing in solid-state nanowires.

Main Results:

• Achieved a high delayed fluorescence quantum yield (Φ_DF = 55%) enabling TADF ASE in CH₂Cl₂ solution.
• Demonstrated a high phosphorescence quantum yield (Φ_P = 27%) in single-crystalline nanowires.
• Observed Fabry-Perot mode phosphorescence lasing at 630 nm.

Conclusions:

• The developed multifunctional material effectively bridges TADF and phosphorescence for advanced lasing applications.
• Oxygen substitution and H-aggregate formation are key strategies for optimizing optical gain and lasing performance.
• This work paves the way for efficient organic lasers utilizing both singlet and triplet excitons.