High open-circuit voltage solid-state dye-sensitized solar cells with organic dye

Abstract

Solid-state dye-sensitized solar cells were fabricated using an organic dye, 2-cyanoacrylic acid-4-(bis-dimethylfluoreneaniline)dithiophene (JK2), which exhibits more than 1 V open-circuit potential (Voc). To scrutinize the origin of high voltage in these cells, transient Voc decay measurements and density functional theroy calculations of the interacting dye/semiconductor surface were performed. A negative conduction band shift was observed due to the favorable dipolar field exerted by the JK2 sensitizer to the TiO2 surface, at variance with heteroleptic Ru(ll)-dyes for which an opposite dipole effect was found, providing an increased Voc. © 2009 American Chemical Society.