Bay-Functionalized Perylene Diimide Derivative Cathode Interfacial Layer for High-Performance Organic Solar Cells

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Nonfullerene acceptors have driven progress in organic solar cells (OSCs).
• Interfacial engineering, particularly cathode interfacial materials (CIMs), is crucial for enhancing power conversion efficiency (PCE).
• Perylene diimide (PDI) small molecules are promising CIMs due to their high electron affinity and mobility, but molecular aggregation can hinder performance.

Purpose of the Study:

• To address the excessive molecular aggregation and crystallinity issues in PDINN, a common PDI-based CIM.
• To investigate the effect of modifying the bay position of PDINN to optimize morphology and charge collection.
• To synthesize and evaluate a novel PDI derivative, PDINN-S, for improved OSC performance and stability.

Main Methods:

• Synthesis of PDINN-S by substituting hydrogen with thiophene at the bay position of PDINN.
• Fabrication of OSC devices utilizing the PM6:Y6 active layer and PDINN-S as the CIM.
• Performance characterization of the OSC devices, including PCE measurements.
• Long-term stability testing of the OSC devices under controlled conditions.

Main Results:

• The synthesized PDINN-S effectively modulated molecular aggregation and film morphology.
• OSCs incorporating PDINN-S achieved an optimal PCE of 16.18%.
• The devices demonstrated excellent operational stability, retaining 80% of their initial PCE after 720 hours in a glovebox.

Conclusions:

• Modifying the PDINN structure at the bay position is an effective strategy to reduce planarity and control aggregation.
• PDINN-S shows significant potential as a high-performance and stable CIM for organic solar cells.
• This work provides valuable insights for the development of future CIMs and the large-scale manufacturing of OSCs.