Conductive Polymer Bridges Mediate High-Performance Flexible Perovskite-Organic Tandem Solar Cells

Area of Science:

• Materials Science
• Renewable Energy
• Solid-State Physics

Background:

• Grain boundaries (GBs) in Br-rich perovskite films critically limit the efficiency and durability of flexible perovskite-organic tandem solar cells (TSCs).
• Defects at GBs cause carrier recombination, lattice expansion, and phase segregation, reducing photovoltaic performance and reliability.

Purpose of the Study:

• To develop a passivation strategy for grain boundaries in perovskite films for enhanced solar cell performance.
• To improve the mechanical robustness and operational stability of flexible perovskite-organic TSCs.

Main Methods:

• A conductive polymer composite was synthesized by incorporating an ionic liquid into polyurethane (PU).
• This composite forms conductive polymer bridges (CPB) across GBs, passivating defects and suppressing halide segregation.
• The CPB enhances carrier diffusion length and reduces nonradiative recombination.

Main Results:

• Rigid wide-bandgap perovskite solar cells (PSCs) achieved a champion efficiency of 20.85% with >1000 h stability.
• Flexible CPB-mediated devices reached 19.03% efficiency and retained 92% PCE after 10,000 bending cycles.
• Rigid and flexible perovskite-organic TSCs achieved 25.92% and 24.02% PCE, respectively, with excellent operational and mechanical stability.

Conclusions:

• The conductive polymer composite effectively passivates GB defects and suppresses halide segregation in perovskite films.
• The developed CPB strategy significantly enhances carrier transport and reduces recombination, leading to improved solar cell performance and durability.
• This approach offers a promising pathway for high-efficiency, mechanically robust flexible perovskite-organic TSCs.