A simple structure copolymer donor based on carboxylated benzodithiophene for polymer solar cells

The design and development of low-cost and efficient photovoltaic materials remain a major challenge for the research and application of polymer solar cells (PSCs). Therefore, developing efficient photovoltaic polymers with simple structure and easy preparation has become an important research topic. Here we report a facilely synthesized electron-donating polymer X1 with a simple chemical structure, which is composed of carboxylated benzo[1,2- b :4,5- b ′]dithiophene (BDT) and thiophene unit. The carboxylate substituents on the BDT unit endowed the polymer with appropriate solubility, low-lying highest occupied molecular orbital (HOMO) energy level, and superior absorption. The PSCs based on X1 as donor showed a high power conversion efficiency of 16.6%, with a remarkable short-circuit current density of 27.07 mA cm −2 . These results demonstrated that X1 is a highly promising candidate for low-cost and efficient PSCs. Furthermore, this study revealed the potential of carboxylated BDT as an effective building block in the research and development of high-performance photovoltaic materials.