A twisted monomeric perylenediimide electron acceptor for efficient organic solar cells

Perylenediimide (PDI)-based materials exhibit great potential as non-fullerene acceptors in bulk-heterojunction (BHJ) organic solar cells (OSCs). Recent investigations have revealed that PDI molecules with a twisted structure could disrupt aggregation of perylene unit. Here, we present a PDI monomer via bay-substitutions with four fused naphthalene units by three-step reactions, named TN-PDI. The introduction of four fused naphthalene rings into the bay positions of PDI unit leads to a strong steric hindrance with a twist angle of 33 degrees between the two PDI subplanes. Blended with a wide-band gap polymer donor (PDBT-T1), the TN-PDI based non-fullerene solar cells show power conversion efficiency (PCE) of 3.0%. Our results indicate that the bay-substitutions with fused aromatic substitutions could be an efficient approach to develop monomeric PDI acceptors.