Progress of Donor and Acceptor Conjugated Polymers and Small molecules for Organic Photovoltaics

Owing to the emergence of π-conjugated polymers and molecules, organic solar cells (OSCs) have been considered as promising trustworthy future technologies. In this context, we present a comprehensive summary of the properties of π-conjugated materials, including their electronic band structure and charge transfer mechanisms. We also discussed the donor/acceptor heterojunction organic solar cells and their operating principle. In fact, we have seen tremendous progress in using organic backbones as donor and acceptor materials in OSCs, owing to their outstanding properties such as high crystallinity, molecular structure susceptibility, adjustable energy levels, and wide absorption range. OSCs' power conversion performance (PCE) surpassed 19% in 2025. These excellent results are realized through optimization of active layer materials design and device engineering.