Syntheses, Charge Separation, and Inverted Bulk Heterojunction Solar Cell Application of Phenothiazine-Fullerene...

Area of Science:

• Organic Chemistry
• Materials Science
• Photovoltaics

Background:

• Phenothiazine-fullerene (PTZ-C60) dyads are explored for organic electronics.
• Understanding structure-property relationships is crucial for optimizing photovoltaic performance.

Purpose of the Study:

• To synthesize and characterize novel PTZ-C60 dyads with varying substitution patterns.
• To investigate the photoinduced electron transfer dynamics within these dyads.
• To evaluate their performance as active materials in inverted organic bulk heterojunction (BHJ) solar cells.

Main Methods:

• Synthesis and characterization of PTZ-C60 dyads.
• Femtosecond transient absorption spectroscopy to study photoinduced electron transfer.
• Fabrication and performance testing of inverted BHJ solar cells using PTZ-C60 dyads and poly(3-hexylthiophene) (P3HT).

Main Results:

• Successfully synthesized PTZ-C60 dyads with fullerene at C-3 or N-positions.
• Established photoinduced electron transfer forming PTZ(•+)-C60(•-) species.
• C-3 substituted dyads exhibited faster charge separation and recombination than N-substituted dyads.
• An inverted BHJ solar cell with a C-3 substituted PTZ-C60 dyad (with polyethylene glycol) achieved 3.5% power conversion efficiency.

Conclusions:

• PTZ-C60 dyads demonstrate efficient intramolecular charge separation and tunable recombination rates.
• The C-3 substitution pattern and specific substituents influence BHJ morphology and device performance.
• PTZ-C60 dyads are promising materials for developing efficient organic photovoltaic devices.