Side chain effect of nonfullerene acceptors on the photovoltaic performance of wide band gap polymer solar cells

• 1,8-Naphthalimide based nonfullerene acceptors were synthesized.
• Different side chains was incorporated into 1,8-naphthalimide based acceptors.
• The molecular aggregation behavior was strongly dependent on the side chains.
• The side chains influenced the molecular crystallinity and film morphology.
• The side chains have a significant effect on photovoltaic performance.

Three 1,8-naphthalimide based small molecules (NI-TAT-NI-C8, NI-TAT-NI-C12, and NI-TAT-NI-C16) have been synthesized and used as acceptor materials for wide band gap polymer solar cells. The side chains of the acceptor molecules have a significant influence on the molecular packing, morphology and photovoltaic performance. The octyl and 2-hexyldecyl substituted small molecular acceptors (NI-TAT-NI-C8 and NI-TAT-NI-C16)are prone to form J-aggregates as films; whereas dodecyl substituted one (NI-TAT-NI-C12) forms H-aggregates. Polymer solar cells with NI-TAT-NI-C12 as the acceptor showed much higher power conversion efficiency than that with NI-TAT-NI-C8 or NI-TAT-NI-C16 as the acceptor. Our results have demonstrated that the molecular packing as well as the photovoltaic performance could be modulated by varying the side chains of acceptor molecules.

Figure optionsDownload as PowerPoint slide