A Composite Interlayer Reconciling Mechanical and Electrical Stability in Perovskite Solar Cells.

Area of Science:

• Materials Science
• Renewable Energy
• Device Physics

Background:

• Interfacial instability in n-type contacts hinders perovskite solar cell (PSC) commercialization due to lattice stress and ion migration.
• This instability degrades electronic order and structural integrity, limiting device performance and longevity.

Purpose of the Study:

• To develop a fully solution-processed n-type interfacial architecture for perovskite solar cells.
• To address the challenges of mechanical stress, ion migration, and electronic stabilization at the n-type contact.
• To create a robust and efficient interface that is insensitive to thickness variations.

Main Methods:

• Integration of a thermally self-crosslinked bathocuproine derivative (c-BCP) with a π-conjugated n-type conductive ink (PBFDO:PEOx).
• Formation of a mechanically continuous and electronically selective junction effective at thicknesses down to 60 nm.
• Characterization of stress redistribution, halide migration suppression, and recombination reduction.

Main Results:

• The composite interlayer effectively redistributes interfacial stress and suppresses halide migration.
• Defect-assisted nonradiative recombination was minimized, improving electronic properties.
• Devices achieved a champion efficiency of 26.37% with over 92% performance retention after 1000 hours of continuous illumination under thermal stress.

Conclusions:

• The developed interfacial architecture resolves the trade-off between interfacial robustness and carrier extraction in n-type contacts.
• This approach provides a generalizable and manufacturing-ready framework for thick, solution-processable n-type contacts.
• The findings enable intrinsically durable and high-efficiency perovskite optoelectronics.