High-Performance Inverted Polymer Solar Cells with Zirconium Acetylacetonate Buffer Layers

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Inverted polymer solar cells (PSCs) offer advantages in stability and processing.
• Efficient charge extraction and transport are crucial for high-performance PSCs.
• Novel buffer layers are needed to overcome performance limitations in PSCs.

Purpose of the Study:

• To investigate the use of solution-processed zirconium acetylacetonate (ZrAcac) as a cathode buffer layer in inverted PSCs.
• To optimize the ZrAcac buffer layer morphology for enhanced device performance.
• To understand the mechanisms behind performance improvements achieved with ZrAcac.

Main Methods:

• Fabrication of inverted PSCs with ZrAcac buffer layers using solution processing.
• Tuning ZrAcac film morphology by varying processing solvents (e.g., chloroform).
• Device characterization including power conversion efficiency (PCE) measurements and analysis of charge transport and recombination dynamics.

Main Results:

• The optimal inverted PSC with a ZrAcac buffer layer achieved a PCE of 9.2%, a ~20% improvement over conventional devices.
• ZrAcac buffer layers facilitated enhanced light harvesting, improved electron transport, and reduced bimolecular recombination.
• A uniform ZrAcac film (~20 nm aggregates) deposited from chloroform proved highly effective, requiring minimal light-soaking time.

Conclusions:

• Solution-processed ZrAcac is a highly effective cathode buffer layer for inverted PSCs.
• Optimizing ZrAcac film morphology is critical for achieving high power conversion efficiencies.
• ZrAcac enables efficient charge extraction and transport, leading to significant performance gains in polymer solar cells.