Thieno[3,4-]pyrrole-4,6-dione-based conjugated polymers for organic solar cells.

Conjugated polymers consisting of electron-rich and electron-deficient units as alternative structures have played important roles in the field of organic solar cells (OSCs). A thieno[3,4-c]pyrrole-4,6-dione (TPD) unit as an electron-deficient unit has been used to construct conjugated polymers for application in fullerene and non-fullerene based OSCs. TPD-based monomers can be simply prepared and TPD-polymers can be synthesized via environmentally friendly direct (hetero)arylation polymerization, providing a possibility for large quantity preparation. TPD-polymers usually have deep frontier energy levels, wide band gaps with absorption onset around 700 nm and good charge transport properties, showing the advantages of high open-circuit voltage, high fill-factor and excellent spectral matching with a small band gap non-fullerene acceptor. From the material design and synthesis and their optoelectrical properties, TPD-polymers have great potential applications in OSCs toward large-area devices. In this review, we provide an overview of TPD-polymers for OSCs in the last ten years, including the design and synthesis of TPD-polymers, and their application in fullerene and non-fullerene OSCs. We will also provide some perspective about the research of TPD-polymers that meet the requirement of OSCs. We hope that our universal summary can stimulate the study of TPD-polymers in the future, especially toward high performance, low cost and stable OSCs.