Application of the Tris(acetylacetonato)iron(III)/(II) Redox Couple in p-Type Dye-Sensitized Solar Cells

An electrolyte based on the tris(acetylacetonato)iron( III)/(II) redox couple ([Fe(acac)(3)](0/1)) was developed for p-type dye-sensitized solar cells (DSSCs). Introduction of a NiO blocking layer on the working electrode and the use of chenodeoxycholic acid in the electrolyte enhanced device performance by improving the photocurrent. Devices containing [Fe(acac)(3)](0/1-) and a perylene-thiophene-triphenylamine sensitizer (PMI-6T-TPA) have the highest reported short-circuit current (J(SC)=7.65 mA cm(-2)), and energy conversion efficiency (2.51%) for p-type DSSCs coupled with a fill factor of 0.51 and an open-circuit voltage V-OC=645 mV. Measurement of the kinetics of dye regeneration by the redox mediator revealed that the process is diffusion limited as the dye-regeneration rate constant (1.7 x 10(8) M-1 S-1) is very close to the maximum theoretical rate constant of 3.3 x 10(8) M-1 S-1. Consequently, a very high dye-regeneration yield (>99%) could be calculated for these devices.