Diazabicyclic Electroactive Ionenes for Efficient and Stable Organic Solar Cells

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Organic solar cells (OSCs) require efficient interlayers to optimize device performance and stability.
• Modulating electrode work function is crucial for efficient charge extraction in OSCs.
• Developing novel materials with tunable optoelectronic properties is key to advancing OSC technology.

Purpose of the Study:

• To develop novel electroactive ionenes as interlayers for organic solar cells.
• To investigate the impact of ionene structure on interfacial properties and device performance.
• To enhance the power conversion efficiency and operational stability of OSCs.

Main Methods:

• Synthesis of electroactive ionenes incorporating caged-shaped diazabicyclic cations and aromatic diimides.
• Fabrication of organic solar cells utilizing these ionenes as interlayers.
• Characterization of interfacial properties, optoelectronic properties, and device performance (e.g., efficiency, stability).

Main Results:

• Ionenes effectively reduce the work function of metal electrodes (Ag, Cu, Au) via strong interfacial dipoles.
• Optimized ionene interlayer enables superior charge transport, desirable crystallinity, and good compatibility with active layers.
• Achieved a power conversion efficiency of 17.44% for PM6:Y6-based OSCs and 18.43% for L8-BO-based OSCs.
• Demonstrated excellent device stability (>1000 hours under illumination) and maintained high efficiency (>16%) with thick interlayers (up to 105 nm).

Conclusions:

• Electroactive ionenes are highly effective interlayers for enhancing organic solar cell performance.
• The developed ionenes offer a promising strategy for improving work function, charge transport, and device stability.
• These findings represent a significant advancement in achieving high-efficiency and stable organic solar cells.