Fluorene-Carbazole Based Self-Assembled Hole Transport Monolayers for Efficient Inverted Perovskite Solar Cells

Area of Science:

• Materials Science
• Photovoltaics
• Organic Electronics

Background:

• Self-assembled monolayers (SAMs) are crucial for improving perovskite solar cells (PSCs).
• Carbazole derivatives are effective hole transport materials in PSCs.
• Limitations include uneven coverage, interface losses, and energy level mismatch.

Purpose of the Study:

• To design and synthesize a new SAM (4PACDF) for enhanced PSC performance.
• To address limitations of traditional SAMs like 4PACz.
• To improve PCE and operational stability of inverted PSCs.

Main Methods:

• Designed and synthesized a novel SAM (4PACDF) with extended conjugation and asymmetric structure.
• Utilized fluorene for extended conjugation in the carbazole-based SAM.
• Incorporated methyl groups to control molecular aggregation and ensure uniform coverage on fluorine-doped tin oxide.

Main Results:

• Achieved high power conversion efficiencies (PCEs) of 25.38% (0.09 cm²) and 24.30% (1 cm²).
• Demonstrated excellent device stability, retaining 89% of initial efficiency after 2000 hours.
• 4PACDF exhibited enhanced dipole moment and improved energy alignment with perovskite layers.

Conclusions:

• The 4PACDF SAM effectively overcomes limitations of previous materials.
• The new SAM significantly boosts both PCE and stability in inverted PSCs.
• 4PACDF represents a promising advancement for high-performance perovskite solar technology.