Random Polymer Donor for High-Performance Polymer Solar Cells with Efficiency over 14.

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Random copolymers are effective for designing polymer donors in polymer solar cells (PSCs).
• Initial naphtho[2,3-c]thiophene-4,9-dione-based copolymer (PBN-Cl) achieved 11.21% power conversion efficiency (PCE) with a low fill factor (FF).

Purpose of the Study:

• To enhance the photovoltaic performance of polymer donors.
• To investigate the effect of incorporating benzo[1,2-c:4,5-c’]dithiophene-4,8-dione (BDD) units into a polymer backbone.

Main Methods:

• Synthesis of a naphtho[2,3-c]thiophene-4,9-dione-based copolymer (PBN-Cl).
• Incorporation of benzo[1,2-c:4,5-c’]dithiophene-4,8-dione (BDD) units into the PBN-Cl backbone to create a random copolymer (PBN-Cl-B80).
• Fabrication and characterization of polymer solar cells using the developed materials.

Main Results:

• The random polymer PBN-Cl-B80, containing 80% BDD units, achieved a significantly higher PCE of 14.05%.
• The enhanced PCE was attributed to a higher FF, improved charge mobility, reduced recombination (bimolecular and trap-assisted), and optimized phase separation.
• The study demonstrated improved photovoltaic performance through strategic copolymer design.

Conclusions:

• Incorporating compatible acceptor units into random polymer donors is a feasible strategy to tune photovoltaic performance.
• The PBN-Cl-B80 copolymer shows promise as an efficient donor material for advanced polymer solar cells.
• Optimizing polymer structure through copolymerization can lead to significant improvements in PSC efficiency.