D-π-A-π-D Structured Diketopyrrolopyrrole-Based Electron Donors for Solution-Processed Organic Solar Cells

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Organic solar cells (OSCs) offer a promising alternative to conventional photovoltaics.
• Developing efficient and stable organic small molecules is crucial for advancing OSC technology.

Purpose of the Study:

• To design and synthesize novel D-π-A-π-D structured organic small molecules for solution-processed OSCs.
• To investigate the impact of heteroatom substitution (sulfur vs. oxygen) on molecular properties and device performance.

Main Methods:

• Synthesis of TDPP-PTCN and FDPP-PTCN using C-H arylation and Suzuki coupling.
• Fabrication of solution-processed OSCs using small molecules as donors and phenyl-C71-butyric acid methyl ester as acceptor.
• Systematic investigation of thermal stability, optoelectronic properties, and photovoltaic performance.

Main Results:

• Achieved power conversion efficiencies (PCEs) of 4.0% for FDPP-PTCN and 5.2% for TDPP-PTCN.
• The highest PCE reported to date for small molecular DPP-phenothiazine-based solution-based OSCs was obtained.
• Demonstrated that replacing oxygen with sulfur in the molecular structure significantly improves photovoltaic performance.

Conclusions:

• The synthesized TDPP-PTCN and FDPP-PTCN molecules show excellent potential for high-performance organic solar cells.
• Heteroatom substitution plays a critical role in optimizing the optoelectronic and photovoltaic properties of organic semiconductors.
• This study highlights a viable strategy for enhancing OSC efficiency through molecular design.