Quinonoid Zwitterion: An Amphiphilic Cathode Interlayer with Initial Thickness-Insensitive and Self-Organizing...

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Orthogonal solvent processability is typically crucial for interfacial materials in organic electronics.
• Effective cathode interlayers are vital for efficient charge extraction in polymer solar cells (PSCs).
• Conventional cathode buffer layers (CBLs) often require specific processing conditions.

Purpose of the Study:

• To investigate the necessity of solvent orthogonality for cathode interlayers in inverted PSCs.
• To evaluate a novel amphiphilic quinonoid zwitterionic molecule (ZW-Bu) as a cathode interlayer.
• To assess the performance and processing flexibility of ZW-Bu compared to traditional materials.

Main Methods:

• Application of ZW-Bu as a cathode interlayer in inverted PSCs with various photoactive systems.
• Performance comparison of devices using ZW-Bu versus zinc oxide (ZnO) CBLs.
• Investigation of ZW-Bu film thickness insensitivity on device efficiency.
• Utilizing ZW-Bu's high surface energy for self-organized CBL formation.

Main Results:

• ZW-Bu functioned effectively as a cathode interlayer without requiring orthogonal solvent processing.
• Devices with ZW-Bu CBLs showed improved performance across three different photoactive systems compared to ZnO.
• Device efficiency was largely unaffected by the initial thickness of the ZW-Bu layer.
• Self-organized ZW-Bu CBLs in P3HT:PC61BM systems achieved desirable efficiencies.

Conclusions:

• Solvent orthogonality is not a mandatory requirement for effective cathode interlayers in inverted PSCs.
• ZW-Bu represents a promising alternative cathode interlayer material offering processing advantages.
• The amphiphilic nature and high surface energy of ZW-Bu enable versatile and efficient device fabrication.