Synthesis, optical, electrochemical and photovoltaic properties of organic dyes containing trifluorenylamine donors

Two new organic dyes based on trifluorenylamine donor and cyanoacrylic acid acceptor have been synthesized and characterized by optical and electrochemical measurements and density functional theory calculations. It is found that the trifluorenylamine donor is beneficial to red-shift the absorption and to lower the oxidation potential when compared to the triphenylamine donor. The variations in the photovoltaic performance of the dyes are corroborated by the dye loading data, incident photon to current conversion efficiency and the interfacial kinetic parameters estimated from the intensity modulated photovoltage/photocurrent spectral measurements. A dye with fluorene and bithiophene segments in the π-linker exhibited device efficiency up to 5.8%. The enhanced power conversion efficiency exhibited by this dye when compared to its analogue containing diphenylaminofluorne donor is attributed to its superior anti-aggregation ability and the comparatively prolonged electron lifetime.