Solubilizing Side Chain Engineering: Efficient Strategy to Improve the Photovoltaic Performance of Novel Benzodithiophene‐Based (X‐DADAD)n Conjugated Polymers

Conjugated polymers represent a promising family of semiconductor materials for thin‐film organic solar cells (OSCs). An efficient approach to improve the photovoltaic performance of conjugated polymers is engineering the side chains attached to the polymer backbone. This work reports the impact of different alkyl substituents on the optoelectronic properties, charge carrier mobilities, thin film morphology, and photovoltaic performance of novel (X‐DADAD)n conjugated polymers incorporating benzo[1,2‐b:4,5‐b′]dithiophene moieties. It has been shown that loading conjugated polymers with appropriate alkyl side chains results in a spectacular performance improvement from 6.8% to 9% in OCSs using a model fullerene acceptor [6,6]‐phenyl‐C71‐butyric acid methyl ester. The obtained results feature side‐chain engineering as a facile and efficient strategy for designing high‐performance conjugated polymers for organic photovoltaics. Novel conjugated copolymers comprising dithienyl‐substituted benzodithiophene blocks bearing different solubilizing side chains are synthesized and explored as electron donor materials for organic solar cells (OCSs). The impact of side chains on optoelectronic properties, charge carrier mobilities and photovoltaic performance of the polymers is demonstrated. The appropriate selection of solubilizing groups boosted the performance of fullerene‐polymer OCSs from 6.8% to 9%.