Multiply Charged Conjugated Polyelectrolytes as a Multifunctional Interlayer for Efficient and Scalable Perovskite...

Area of Science:

• Materials Science
• Renewable Energy
• Organic Electronics

Background:

• Perovskite solar cells (PeSCs) are promising renewable energy devices.
• Hydrophobic hole-extraction layers (e.g., PTAA) can hinder perovskite formation.
• Interlayers are crucial for optimizing PeSC interfaces.

Purpose of the Study:

• To synthesize and investigate anionic conjugated polyelectrolytes (CPEs) as interlayers in PeSCs.
• To explore the impact of varying side-chain ionic density on PeSC performance.
• To enhance perovskite crystallization, wettability, and device stability.

Main Methods:

• Synthesis of poly(fluorene-co-phenylene) based CPEs with varying ionic densities (MPS2-TMA, MPS4-TMA, MPS6-TMA).
• Fabrication of inverted PeSCs utilizing CPEs as interlayers on a PTAA layer.
• Characterization of device performance, including open-circuit voltage and power conversion efficiency.
• Analysis of trap densities using frequency-dependent capacitance measurements.

Main Results:

• CPE interlayers significantly improve perovskite wettability on PTAA, leading to enhanced device performance.
• Increasing ionic density in CPEs (MPS2-TMA to MPS6-TMA) improves perovskite wetting, defect passivation, and crystal growth.
• Open-circuit voltage increased from 1.06 V to 1.11 V with higher ionic density.
• A large-area (1 cm²) PeSC with MPS6-TMA achieved 18.38% power conversion efficiency with negligible hysteresis and stable output.

Conclusions:

• Anionic conjugated polyelectrolytes serve as effective interlayers for inverted PeSCs.
• Side-chain ionic density is a critical parameter for optimizing PeSC performance through improved interfacial properties.
• The developed MPS6-TMA interlayer enables high-efficiency, stable, and large-area perovskite solar cells.