Tailored Monolayer Co-Assembly for Enhanced Efficiency and Stability in Inverted Perovskite Solar Cells

Area of Science:

• Materials Science
• Renewable Energy
• Nanotechnology

Background:

• Self-assembled monolayers (SAMs) are crucial as hole-selective interlayers in perovskite solar cells (PSCs).
• Limitations of current SAMs include incomplete coverage and poor molecular ordering, leading to interfacial defects and recombination losses in PSCs.

Purpose of the Study:

• To develop a novel interfacial engineering strategy for high-performance and durable p-i-n perovskite solar cells.
• To overcome limitations of single-component SAMs by creating a mixed monolayer with improved molecular packing and defect passivation.

Main Methods:

• Development of a bulky methylthio-functionalized carbazole-based SAM (S-2PACz).
• Implementation of a sequential co-assembly strategy using cysteine (Cys) and S-2PACz.
• Formation of a mixed Cys-S-2PACz monolayer through competitive adsorption and cooperative anchoring.

Main Results:

• The mixed Cys-S-2PACz monolayer exhibited denser packing, improved ordering, and effective passivation of interfacial defects.
• Enhanced perovskite crystallization, optimized energy-level alignment, and facilitated hole extraction were observed.
• Perovskite solar cells incorporating Cys-S-2PACz showed higher power conversion efficiency and reduced recombination losses.

Conclusions:

• The competitive co-assembly strategy provides a scalable route to tailored SAM architectures for high-performance PSCs.
• The mixed Cys-S-2PACz monolayer significantly improved the thermal, operational, and outdoor stability of the devices.
• This work demonstrates the potential of mixed SAMs for advancing perovskite solar cell technology.