Efficient Bulk‐Heterojunction Solar Cells Based on Symmetrically Disubstituted Polyalkyloxythiophenes at Low Synthetic Complexity

The aim of this study is to present a challenging insight into the molecular design and architecture optimization of two cost-effective conjugated polymers and their adoptions in bulk heterojunction fullerene-based solar cells. The new polymers, with repeating units based on symmetrically disubstituted polyalkyloxythiophenes have been prepared with simple procedures and have been employed as electron-donor materials for polymer solar cells. A comparative study with monosubstituted polyalkyloxythiophene has evidenced a more favorable active morphology, improved charge mobility, and higher power conversion efficiency for the newly prepared disubstituted polymers. Photoconversion ability further increases when a thin layer of a cationic polyelectrolyte is coated on the surface of the photoactive blend, thus facilitating electron transport. Finally, the prepared polymers were evaluated according to a figure of merit based on their synthetic complexity and conversion efficiency, resulting in particularly suitable for large-scale production.