A Novel Self-Assembled Hole-Transporting Monolayer with Extending Conjugation for Inverted Perovskite Solar Cells

Area of Science:

• Materials Science
• Renewable Energy
• Organic Electronics

Background:

• Self-assembled monolayers (SAMs) are crucial hole-transporting materials in inverted perovskite solar cells (PSCs).
• Structural engineering of SAMs is a key strategy for improving PSC performance and stability.

Purpose of the Study:

• To design and synthesize a novel SAM with extended conjugation, E-CbzBT, for enhanced PSC performance.
• To investigate the impact of E-CbzBT's unique molecular structure on perovskite film formation and device characteristics.

Main Methods:

• Synthesis of E-CbzBT and its characterization.
• Fabrication of inverted PSCs using E-CbzBT and CbzBT as hole-transporting layers.
• Performance evaluation of PSCs through power conversion efficiency (PCE) measurements.
• Assessment of device stability under ambient and thermal stress.

Main Results:

• E-CbzBT exhibits an asymmetric, noncoplanar, screw-shaped configuration, enabling uniform and tight packing on ITO substrates.
• The uniform packing of E-CbzBT enhances perovskite precursor wettability, leading to improved perovskite crystallinity and reduced interfacial trap density.
• Inverted PSCs with E-CbzBT achieved a champion PCE of 25.15%, outperforming CbzBT-based devices (24.06%).
• E-CbzBT-based PSCs demonstrated superior ambient and thermal stability compared to control devices.

Conclusions:

• Extending conjugation in SAMs is an effective strategy for developing advanced hole-transporting materials for perovskite solar cells.
• E-CbzBT offers significant improvements in both efficiency and stability for inverted PSCs.
• This work paves the way for further optimization of SAMs to advance perovskite solar cell technology.