Effect of different side chains on alternating copolymers of benzodithiophene and thiophene in organic solar cells

Abstract

Polymeric semiconductors offer the dual advantages of lightness and flexibility, facilitating the large‐scale production of organic electronic devices. In the present research, electron donor polymers were synthesized incorporating high electron density aromatic units, specifically benzodithiophene (BDT) and thiophene (Th), to explore their efficacy in organic electronics. This systematic study focused on evaluating the impact of varying side chains on the material properties of these polymers. It was found that polymers with Th side chains exhibited significantly enhanced thermal stability, approximately 100°C higher than their alkoxide side chain counterparts. For the polymer PEHO‐BDT3HT, a bandgap value of around 1.6 eV was obtained. Furthermore, binary devices were developed using these novel copolymers, among which PDT‐BDT3HT demonstrated superior photovoltaic performance, achieving a power conversion efficiency of 1.56% without any optimization. This work not only sheds light on the influence of side chain variations in polymer properties but also showcases the potential of BDT and Th‐based copolymers in the field of organic electronics.