Hexanary blends: a strategy towards thermally stable organic photovoltaics

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Non-fullerene organic solar cells (NFOSCs) offer high initial power conversion efficiency (PCE).
• NFOSCs suffer from poor thermal stability, particularly with thick active layers, limiting their practical application.
• Current NFOSCs often face degradation issues under thermal stress.

Purpose of the Study:

• To enhance the thermal stability of non-fullerene based organic solar cells.
• To explore the use of multi-component acceptor mixtures in NFOSCs.
• To enable high-throughput processing and large-area fabrication of stable NFOSCs.

Main Methods:

• Blending a donor polymer with five structurally similar non-fullerene acceptors.
• Fabricating hexanary blend organic solar cells.
• Conducting thermal annealing tests at 130°C for 23 days in the dark and inert atmosphere.

Main Results:

• Achieved power conversion efficiency (PCE) up to 17.6% in hexanary devices.
• Demonstrated unaffected device performance after prolonged thermal annealing (23 days at 130°C).
• Confirmed high thermal stability for active layer thicknesses up to 390 nm.

Conclusions:

• A generic strategy using multi-component acceptor mixtures significantly improves NFOSC thermal stability.
• This approach overcomes critical limitations for thick active layers, benefiting high-throughput processing.
• The findings pave the way for developing stable, large-area organic solar cells.