A computational investigation of the effects of changes of donor–acceptor linker length and acceptor on electronic spectra of small-molecule single-component organic solar cells

Abstract

Small-molecule single-component organic solar cells (SM-SCOSCs) have great potential for commercial application. However, the effects of changes of donor–acceptor linker length and acceptor unit of small molecules of active layers on their photoelectric properties are still not well understood. In this work, four state-of-the-art dyads 1–4 were selected to investigate these effects since dyad 4 created the highest power conversion efficiency (PCE) of 5.34% of SM-SCOSC; and their electronic structures were investigated. The results indicate that increasing the length of the donor–acceptor connecting bridge leads to a decrease in exciton binding energy, and so does replacing the acceptor component PC61BM with PC71BM. Furthermore, the simulated electronic absorption spectrum of dyad 4 is enhanced with respect to others. We also find that the introduction of PC71BM creates more channels for transitions from local excited states to charge transfer states. This work gains a deep insight into the relationship between molecular structure and performance of SM-SCOSC.