Self-Assembled Ionic Liquid for Highly Efficient Electron Transport Layer-Free Perovskite Solar Cells

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Electron transport layer (ETL)-free perovskite solar cells (PSCs) offer cost advantages due to fewer layers but suffer from lower photovoltaic performance compared to ETL-containing devices.
• Improving the efficiency of ETL-free PSCs is crucial for their practical application and widespread adoption in the renewable energy sector.

Purpose of the Study:

• To design and synthesize a novel ionic liquid for enhancing the performance of ETL-free PSCs.
• To investigate the self-assembly behavior of the ionic liquid on conductive substrates and its impact on interfacial properties.
• To demonstrate a new strategy for fabricating highly efficient ETL-free PSCs.

Main Methods:

• Synthesis of a hydroxyethyl-functionalized imidazolium iodide ionic liquid.
• Determination of the single crystal structure of the synthesized ionic liquid.
• Self-assembly of the ionic liquid on a conductive substrate to form an interfacial layer.
• Fabrication and characterization of ETL-free PSCs using the modified substrate.

Main Results:

• The self-assembly of the ionic liquid effectively lowers the work function of the conductive substrate.
• Enhanced interfacial electron extraction and suppressed interfacial charge recombination were observed.
• The power conversion efficiency of ETL-free PSCs improved significantly from 9.01% to 17.31% after ionic liquid self-assembly.

Conclusions:

• The developed hydroxyethyl-functionalized imidazolium iodide ionic liquid serves as an effective interfacial layer for ETL-free PSCs.
• Self-assembly of ionic liquids provides a viable approach to enhance electron extraction and reduce recombination, leading to higher device efficiency.
• This study presents a promising new method for fabricating efficient and potentially lower-cost ETL-free perovskite solar cells.