Self-Assembled Bilayers with Improved Solvent Resistance for Stable Inverted Perovskite Solar Cells

Area of Science:

• Materials Science
• Photovoltaics
• Interface Engineering

Background:

• Self-assembled monolayers (SAMs) on transport layers in perovskite solar cells (PVSCs) often desorb during processing and operation.
• This desorption reduces power conversion efficiency (PCE) and leads to device degradation.
• Stabilizing SAMs is critical for improving PVSC performance and longevity.

Purpose of the Study:

• To develop a robust interface strategy for stabilizing SAMs in PVSCs.
• To enhance the performance and operational stability of perovskite solar cells.
• To investigate the role of cross-linked organosilane bilayers in preventing SAM desorption and mitigating interfacial defects.

Main Methods:

• Constructed robust self-assembled bilayers (SABs) using n-propyltrimethoxysilane (PTMS) and (3-mercaptopropyl)trimethoxysilane (MPTMS) on Me-4PACz SAMs for NiO_x modification.
• Utilized the cross-linked organosilane network to form a protective layer against solvent-induced desorption and fill molecular voids.
• Leveraged the thiol group in MPTMS for strong interaction with undercoordinated Pb²⁺ at the perovskite interface.

Main Results:

• The NiO_x/Me-4PACz/MPTMS based PVSCs achieved a high PCE of 24.9%.
• The devices demonstrated a T₈₀ lifetime of 475 hours under continuous 1 sun illumination in air.
• Control devices without the SABs showed a lower PCE of 23.3% and significantly shorter lifetimes.

Conclusions:

• The developed SAB strategy effectively stabilizes SAMs, preventing desorption and improving interface compactness.
• The robust interface significantly enhances both the power conversion efficiency and long-term stability of perovskite solar cells.
• This approach offers valuable insights for designing high-performance and stable PVSCs through interface engineering.