Relation between the Electronic Properties of Regioregular Donor-Acceptor Terpolymers and Their Binary Copolymers

Area of Science:

• Materials Science
• Organic Electronics
• Polymer Chemistry

Background:

• Designing new π-conjugated polymers is crucial for advancing organic electronic devices.
• Understanding the relationship between polymer structure and optoelectronic properties is key for material design.

Purpose of the Study:

• To investigate the correlation between the properties of regioregular terpolymers and their corresponding binary copolymers.
• To establish a predictive model for designing new π-conjugated polymers with desired optoelectronic characteristics.

Main Methods:

• Synthesis and characterization of seven regioregular terpolymers with a common electron-deficient acceptor (diketopyrrolopyrrole) and varying electron-rich donor units.
• Optical band gap and energy level measurements (frontier orbital energies).
• Fabrication and characterization of bulk heterojunction solar cells using terpolymers and copolymers.

Main Results:

• A direct correlation was established between terpolymer properties and the arithmetic average of parent binary copolymer properties.
• Optical band gap and frontier orbital energies of terpolymers accurately matched the arithmetic average of copolymers.
• Open-circuit voltage in bulk heterojunction solar cells followed the same arithmetic averaging rule.

Conclusions:

• The arithmetic averaging rule for terpolymer properties provides a universal tool for designing new π-conjugated polymers.
• Semiempirical quantum chemical modeling supports the observed relationships and offers theoretical insights.
• This predictive capability can accelerate the development of efficient organic electronic materials.