Narrow-band gap Benzodipyrrolidone (BDPD) based donor conjugated polymer: A theoretical investigation

Extending conjugation length, involving strong π–π interactions and large electron-withdrawing functional groups have been experimentally proved to be the efficient strategies for performance enhancement of donor–acceptor (D–A) polymers used in organic solar cells. In this paper, considering above strategies, a series of novel D–A conjugated polymers have been designed and theoretically investigated on their electronic structures, energy levels, and optical absorption, using first principles calculation methods under the PBE0/6-311G (d,p) and TD-B3LYP/6-31G (d,p) level. The results show, compared with those base polymers, the newly designed polymers exhibit better performances including narrower band gaps, deeper HOMO energy levels (broadband optical absorption), and better theoretical power conversion efficiencies (PCEs) predicted by Scharber diagrams. These polymers can be used as the active layers in high performance organic solar cells.