Exploration of the Direct Arylation Polymerization Method for the Practical Application of Conjugated Materials: Synthetic Scale-Up, Solar Cell Performance, and Cost Analyses

This study reports the scalability of direct arylation polymerization (DArP) batch reactions for the preparation of poly(3-hexylthiophene) (P3HT) using the Herrmann–Beller catalyst combined with a tertiary phosphine in the green solvent 2-methyltetrahydrofuran on scales ranging from 0.5 to 10 g. The physical properties of these DArP polymers are compared to those resulting from P3HT prepared via Grignard metathesis (GRIM) on a 130 g scale. Both DArP and GRIM methods are found to produce highly regioregular polymers with no evidence of β-defects and the polymers are found to exhibit comparable device performance as donor materials in bulk heterojunction organic solar cells. Purification studies coupled with device measurements highlight the necessity to carefully address the presence of impurities in materials produced from large-scale DArP batch reactions. Economic analyses reveal that the cost involved in the preparation of P3HT via DArP or GRIM procedures are comparable per gram of product and show that the most expensive component is unique for each method.