Highly Efficient and Stable Organic Solar Cells Enabled by a Commercialized Simple Thieno[3,2-b]thiophene Additive

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Optimizing nanomorphology is crucial for organic solar cell (OSC) performance and stability.
• High-boiling point solvent additives often require complete removal for operational stability.

Purpose of the Study:

• To investigate the use of solid additives (SAs) for enhancing OSC morphology and performance.
• To explore the effects of thieno[3,2-b]thiophene (TT) and 3,6-dibromothieno[3,2-b]thiophene (TTB) as SAs in OSCs.

Main Methods:

• Theoretical simulations and experimental analysis of TT and TTB interactions with donor (PM6) and acceptor (Y6) materials.
• Fabrication and characterization of OSCs using TT and TTB as solid additives.
• Evaluation of photovoltaic performance, charge carrier mobility, recombination losses, thermal stability, and photostability.

Main Results:

• TT and TTB selectively intercalate between donor and acceptor molecules, improving molecular packing and crystallinity.
• TT treatment of PM6:Y6 based OSCs resulted in enhanced morphology, charge transport, and reduced recombination, achieving 17.75% power conversion efficiency (PCE).
• TT treatment demonstrated excellent thermal stability (T80 > 2800 h at 65°C) and photostability, and was successfully applied to D18:L8-BO based OSCs, reaching 18.3% PCE.

Conclusions:

• Solid additives can effectively optimize blend morphology in OSCs, leading to improved photovoltaic performance.
• TT treatment offers a promising strategy for developing highly stable and efficient organic solar cells.
• The use of appropriate solid additives is vital for enhancing both the efficiency and operational lifetime of OSCs.