Polythiophene and its derivatives for all-polymer solar cells

All-polymer solar cells (all-PSCs), employing conjugated polymers for both polymer donors and acceptors within the active layer, offer numerous benefits, such as outstanding mechanical flexibility, device longevity, and suitability for roll-to-roll manufacturing processes. Recently, polymerized small molecule acceptors have emerged as pivotal contributors to the advancement of all-PSCs, particularly in enhancing power conversion efficiencies. Nevertheless, the quest for high-performance and cost-effective polymer donors for all-PSCs persists, presenting a bottleneck in the broader-scale production. Polythiophene and its derivatives (PTs) have garnered renewed attention owing to their simplicity, cost-effectiveness, and scalability. The development of PT-based all-PSCs stands as a promising avenue toward achieving high efficiency, low cost, and enhanced stability in organic solar cells. This review centers on PT-based all-PSCs, elucidating the design principles of polymer acceptors compatible with classic P3TH and outlining strategies for novel PTs to attain high efficiency. Additionally, we offer comprehensive insights into device optimization strategies and discuss the parameters pertinent to PT-based all-PSCs, with the aim of advancing research in this promising field of renewable energy. We review polythiophene and its derivative (PT)-based polymer donors for all-PSCs, focusing on material design, morphology optimization strategies, and the selection and design of polymer acceptors that complement their properties.