A red to blue series of push–pull dyes for NiO based p-DSSCs

Finding efficient dyes for NiO photocathodes either for inverse or tandem DSSCs is essential to developing these promising low-cost solar cells. This paper reports the design, synthesis and physical property characterization of four new triphenylamine–bithiophene push–pull dyes with acceptors of increasing electronic affinity, in order to shift their absorption to the red region of the visible spectrum. The dyes were tested in a p-type DSSC configuration with 850 nm NiO ink-jet printed photocathodes and their performances were compared with that of the reference dye P1. With an iodine electrolyte, one of the dyes, possessing a 1,3-diethyl-2-thiobarbituric acceptor, shows superior performance to P1, with PCE reaching 0.124% and a JSC of 4.32 mA cm−2.