Highly efficient triarylene conjugated dyes for sensitized solar cells

A new series of organic dyes containing a triarylamine donor group, a triarylene-linked bridging moiety, and a cyanoacrylic acid acceptor group were synthesized through a simple procedure in high yields. A selected set of substituents were added onto the phenyl group ortho to the cyanoacrylic acid in order to examine their influences on the performance of dye-sensitized solar cells (DSSCs). Their photochemical behaviors were examined under AM1.5 solar condition (100 mW cm−2). A typical device made with a compound containing a -CF3 substituent (PSP-CF3) displayed a short-circuit current (Jsc) 15.16 mA cm−2, an open-circuit voltage (Voc) 0.68 V, a fill factor (ff) 0.68, corresponding to an overall conversion efficiency of 7.0% and a maximal monochromatic incident photon-to-current conversion efficiency (IPCE) 78%. Their photophysical and electrochemical properties were analyzed with the aid of a time-dependent density functional theory (TDDFT) model with the B3LYP functional. Their HOMO and LUMO energy levels are verified by both electrochemical measurements and theoretical calculations.