Ternary System with Controlled Structure: A New Strategy toward Efficient Organic Photovoltaics

Area of Science:

• Materials Science
• Organic Electronics
• Renewable Energy

Background:

• Binary organic photovoltaics (OPVs) performance is limited by disordered bulk heterojunction (BHJ) structures in simple ternary blends.
• Restrictions include isolated domains and poor metal-semiconductor contacts, hindering higher OPV efficiency.

Purpose of the Study:

• To introduce a controlled ternary (C-ternary) OPV structure with improved donor/acceptor arrangement.
• To overcome the limitations of disordered BHJ structures in achieving high-performance OPVs.

Main Methods:

• Fabrication of C-ternary OPVs using a sequential solution process.
• Sequential spin-coating of the second acceptor and a donor/acceptor binary blend.
• Device optimization to enhance performance.

Main Results:

• C-ternary OPVs demonstrated significant PCE enhancements of 14-21% over simple ternary blends.
• Achieved best PCEs of 10.7% (fullerene-based) and 11.0% (fullerene-free) OPVs.
• Fullerene-free OPVs showed an average PCE of 10.4%, closely matching the certified 10.32%.

Conclusions:

• The C-ternary structure offers a more controlled BHJ morphology for enhanced OPV performance.
• Sequential solution processing is an effective strategy for fabricating high-efficiency ternary OPVs.
• The developed fullerene-free OPVs show promising efficiency for commercial applications.