Novel Benzo[1,2-b:4,5-b′]dithiophene–Benzothiadiazole Derivatives with Variable Side Chains for High-Performance Solar Cells

Graphical Low bandgap copolymers are prepared by incorporating thiophene-modified benzo[1,2- b :4,5- b ′]dithiophene and alkyloxy or fluorine-modified benzothiadiazole as donor and acceptor units. These copolymers exhibit a high open-circuit voltage and short-circuit current density. Good power conversion efficiencies are demonstrated in solar cell studies, indicating their promising photovoltaic application as donor materials.