Beyond the Surface: Three-Dimensional Distribution and Defect Passivation of Self-Assembled Monolayers in Perovskite...

Area of Science:

• Materials Science
• Renewable Energy
• Nanotechnology

Background:

• Self-assembled monolayers (SAMs) are crucial for tuning interfacial properties in perovskite solar cells (PSCs).
• Traditionally, SAMs are viewed as 2D surface modifiers, limiting their perceived role in device optimization.
• Understanding the full dimensional impact of SAMs is key to advancing PSC technology.

Purpose of the Study:

• To investigate the three-dimensional (3D) nature of perfluorinated silanol-based SAMs on perovskite films.
• To determine the impact of this 3D structure on PSC photovoltaic performance and stability.
• To explore the potential of SAMs as volumetric modifiers for perovskite optoelectronics.

Main Methods:

• Application of perfluorinated silanol-based SAMs onto perovskite films.
• High-resolution 3D nanoscale secondary ion mass spectrometry (3D nanoSIMS) for mapping SAM distribution.
• Photovoltaic performance and stability testing of modified PSCs.

Main Results:

• SAMs exhibit a 3D distribution, penetrating perovskite films up to ~100 nm.
• Selective anchoring of SAMs at grain-boundary iodine-deficient regions was observed.
• Dual surface-bulk passivation led to reduced nonradiative recombination and improved interfacial energetics.
• Enhanced photovoltaic performance and increased environmental stability of PSCs were achieved.

Conclusions:

• Perfluorinated silanol-based SAMs function as 3D volumetric modifiers, not just 2D surface layers.
• This 3D passivation strategy significantly improves perovskite solar cell performance and stability.
• SAMs offer a pathway for molecular-level engineering in perovskite optoelectronics.