Dimerized Small-Molecular Acceptor Enables the Organic Bulk-Heterojunction Layer with High Thermal Stability

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Organic bulk-heterojunctions with non-fullerene acceptors (NFAs) offer improved spectral response and photocurrent in organic photodiodes.
• Industrial commercialization of organic materials is hindered by poor thermal stability, often caused by NFA small molecule aggregation during heating.

Purpose of the Study:

• To address the thermal stability limitations of highly efficient NFAs.
• To design and synthesize novel NFA dimers for enhanced thermal stability in organic photovoltaic devices.

Main Methods:

• Designed and synthesized two IDIC-based NFA dimers: IDIC-T Dimer and IDIC-TT Dimer.
• Evaluated the thermal stability of bulk-heterojunction (BHJ) layers incorporating these dimers.
• Compared the performance and stability against a BHJ layer using the IDIC-4Cl monomer.

Main Results:

• Organic photovoltaic devices based on the NFA dimer achieved a power conversion efficiency of 9.44%.
• The synthesized NFA dimers exhibited significantly improved thermal stability compared to the IDIC-4Cl monomer.
• The dimer-based BHJ layer demonstrated superior resistance to aggregation under thermal stress.

Conclusions:

• NFA dimers offer a promising strategy to overcome thermal stability issues in organic photodiodes.
• The developed NFA dimers pave the way for more industrially practical polymer/small-molecule organic photovoltaic systems.
• Enhanced thermal stability in NFAs is crucial for the successful integration and operation of organic electronic devices.