Planar conjugated polymers containing 9,10-disubstituted phenanthrene units for efficient polymer solar cells

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Development of efficient donor materials is crucial for advancing polymer solar cells (PSCs).
• Phenanthrene-based conjugated polymers offer promising optoelectronic properties for photovoltaic applications.

Purpose of the Study:

• To synthesize and characterize novel conjugated polymers incorporating 9,10-disubstituted phenanthrene (PhA) as a donor unit.
• To evaluate the performance of these polymers in bulk heterojunction (BHJ) polymer solar cells (PSCs).

Main Methods:

• Synthesis of four novel conjugated polymers (P1-4) using 9,10-disubstituted phenanthrene and 5,6-bis(octyloxy)benzothiadiazole units.
• Characterization of polymer properties including bandgap, HOMO energy levels, and hole mobility.
• Fabrication and testing of BHJ PSCs using P1-4:PC71BM active layers and FN-C60 interfacial layers.

Main Results:

• Synthesized polymers exhibit medium bandgaps (~2.0 eV), low-lying HOMO levels (< -5.3 eV), and high hole mobilities (3.6 × 10⁻³ to 0.02 cm² V⁻¹ s⁻¹).
• The best performing PSC achieved a power conversion efficiency (PCE) of 4.24% using a P1-4:PC71BM active layer and FN-C60 interfacial layer.

Conclusions:

• The synthesized conjugated polymers demonstrate suitability for use in high-efficiency BHJ PSCs.
• 9,10-disubstituted phenanthrene units are identified as effective donor materials for developing advanced polymer solar cells.