A tetrahydropyrene-based organic dye for solar cell application

Abstract

A novel tetrahydropyrene-based D–π–A organic dye D2 was designed and synthesized for the first time, featuring 4,5,9,10-tetrahydropyrene as a π conjugation linker to bridge the diphenylamine unit and the thienyl acrylic acid moiety. Its counterpart D1 was prepared for comparison, where biphenyl was used as the linker. Both dyes were characterized by photophysical, electrochemical, and theoretical computational methods. It was found that the introduction of two ethylene groups on the C2, C2′ and C6, C6′ of the biphenyl in D2 can prevent the rotation of the adjacent phenyl rings, and ensure the coplanarity of the bridge. As a result, the maximum absorption peak (λ_max) of D2 was 29 nm red shifted as compared with D1. Nanocrystalline TiO₂-based dye-sensitized solar cells were fabricated using the dyes as light harvesting sensitizers, and exhibited power conversion efficiencies of 6.75% for D2 and 4.73% for D1 under AM 1.5 conditions.