Structure and Photovoltaic Properties of (E)-2-Cyano-3-[4-(diphenylamino)phenyl]acrylic Acid Substituted by tert-Butyl Groups

(E)-3-{4-[Bis(4-tert-butylphenyl)amino]phenyl -2-cyano-acrylic acid and its related compounds were synthesized by the Knoevenagel condensation of the corresponding 4-aminobenzaldehydes with cyanoacetic acid. Cyclic voltammetry measurements showed that these organic dyes exhibited reversible oxidation waves. The tert-butyl substituents also decreased molecular stacking in the crystals, thus affecting the photovoltaic properties of the dyes. A solar cell using the tert-butylsubstituted dye exhibited higher performance than that for the analog without tert-butyl group substitution.