Precise synthesis of conjugated polymers via reducing homocoupling defects

In recent years, π-conjugated polymers (CPs) have garnered significant attention for their versatile applications in optoelectronics, energy storage, and sensing technologies. This heightened interest stems from their advantageous properties, including tunable energy levels, intrinsic flexibility, and solution processability. Despite these merits, the synthesis of CPs, particularly alternating CPs, predominantly relies on transition metal-catalyzed cross-coupling reactions, such as Stille, Suzuki, Negishi, Sonogashira, Kumada, Sonogashira and direct arylation polymerization. However, these methodologies often result in homocoupling (hc) defects and substantial batch-to-batch variability, which pose significant barriers to the advancement and commercialization of CPs. This review systematically examines these challenges, offering detailed mechanistic insights into defect formation and highlighting recent strategies aimed at mitigating these issues while enhancing polymer properties. By emphasizing these mechanistic aspects, the review underscores the critical role of interdisciplinary approaches in advancing CP-based technologies, particularly for organic field-effect transistors (OFETs), organic solar cells (OSCs), and organic light-emitting diodes (OLEDs).