Synthetic Control of Structural Order in N-Alkylthieno[3,4-c]pyrrole-4,6-dione-Based Polymers for Efficient Solar Cells

Intense interdisciplinary research in the field of organic photo-voltaics (OPVs) has led to a significant increase in their power conversion efficiencies (PCEs) over the past decade.1 One of the most important advances in OPVs has been the introduction of the bulk heterojunction (BHJ) architecture,2 in which the photoactive thin film consists of an interpenetrating blend of electron donor and electron acceptor components. Extensive research efforts have focused on improving the polymeric electron donor component of the BHJ while retaining fullerene derivatives as the electron acceptor.3 Key developments have involved narrowing the polymer bandgap, in order to better match the optical absorption with the solar spectrum, and optimizing the energy level offsets with fullerene to achieve maximum open-circuit voltage (Voc).4 For the design of new polymers, non-energetic parameters such as those that influence the physical interaction between the bulk polyme