A 2,7-pyrene-based dye for solar cell application

Abstract

Substituting pyrenes at the 2,7-positions is synthetically challenging because of the presence of a nodal plane in the HOMO and LUMO, which lies perpendicular to the molecule and passes through the 2- and 7-positions. Thus, there are few reports about 2,7-substituted pyrenes. Here, a distinct D–π–A structured 2,7-substituted pyrene dye ICP-3 was successfully synthesized, where a diphenylamine unit and thienyl acrylic acid moiety are located at C-2,7 positions of the pyrene, and the pyrene functions as a linker to bridge them. The DFT calculations show that no nodal plane through the 2- and 7-carbon atoms was observed in the HOMO and LUMO when the donor and the acceptor were attached, indicating effective charge transfer in the molecule upon light excitation. The ICP-3 was used as sensitizer for dye-sensitized solar cells, showing a power conversion efficiency of 4.1% under AM 1.5 conditions.