A Flexible Side-Chain Dispersant Enables Uniform Self-Assembled Monolayers for 18.67% Organic Solar Cells.

Area of Science:

• Materials Science
• Organic Electronics
• Surface Chemistry

Background:

• Self-assembled monolayers (SAMs) on indium tin oxide (ITO) often aggregate, leading to poor interfacial coverage.
• This aggregation limits charge extraction and the overall performance of organic solar cells (OSCs).

Purpose of the Study:

• To design and synthesize a novel dispersant molecule, 2ICzMPE, to control SAM formation on ITO.
• To improve interfacial uniformity and enhance charge extraction efficiency in OSCs.

Main Methods:

• Synthesis of 2ICzMPE, a carbazole derivative with dipolar characteristics and flexible side chains.
• Investigating the effect of 2ICzMPE on the interfacial structure and energy level alignment of SAMs on ITO.
• Fabricating and characterizing organic solar cells (OSCs) using the modified interface.

Main Results:

• 2ICzMPE effectively suppressed molecular aggregation of 2PACz on ITO surfaces.
• The dispersant molecule promoted a more uniform interfacial structure through interactions with the ITO surface.
• Optimized energy level alignment led to enhanced charge extraction, reduced carrier recombination, and improved charge transport.
• Power conversion efficiency (PCE) of the OSCs increased from 17.51% to 18.67%.

Conclusions:

• The designed dispersant molecule 2ICzMPE offers a simple and effective strategy for creating high-quality SAM interfaces.
• This approach can significantly enhance the performance and promote the scalable application of organic solar cells.