Multidentate Fullerenes Enable Tunable and Robust Interfacial Bonding for Efficient Tin-Based Perovskite Solar Cells

Area of Science:

• Materials Science
• Renewable Energy
• Nanotechnology

Background:

• Tin-based perovskite solar cells (TPSCs) face efficiency limitations due to interfacial issues between perovskite and electron transport layers (ETLs).
• Energy level mismatch and weak interactions at the interface hinder charge extraction and device performance.

Purpose of the Study:

• To synthesize and evaluate novel multidentate fullerene molecules as interfacial layers in TPSCs.
• To improve electron extraction, defect passivation, and overall device efficiency and stability.

Main Methods:

• Synthesis of four fullerene derivatives (FM3, FM4, FM5, FM6) with varying diethylmalonate groups.
• Incorporation of these molecules as interfacial layers in TPSC devices.
• Characterization of interfacial properties, energy levels, and device performance.

Main Results:

• Increasing functional groups on fullerenes led to shallower LUMO levels and enhanced interfacial interactions.
• FM5 exhibited optimal energy levels and strong perovskite interaction, boosting electron extraction and passivation.
• FM5-based devices achieved a champion efficiency of 15.05%, outperforming PCBM and other FM derivatives.
• FM5-based devices showed remarkable stability, retaining over 90% efficiency after 300 hours of air exposure.

Conclusions:

• Multidentate fullerene interfacial layers effectively address TPSC efficiency bottlenecks.
• FM5 represents a promising material for high-efficiency and stable tin-based perovskite solar cells.
• The molecular design of interfacial layers is crucial for optimizing charge transfer and device longevity.