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 shortcircuit current (JSC=7.65 mA cm2 ), and energy conversion efficiency (2.51%) for p-type DSSCs coupled with a fill factor of 0.51 and an open-circuit voltage VOC=645 mV. Measurement of the kinetics of dye regeneration by the redox mediator revealed that the process is diffusion limited as the dyeregeneration rate constant (1.7 108 m 1 s 1 ) is very close to the maximum theoretical rate constant of 3.3 108 m 1 s 1 . Consequently, a very high dye-regeneration yield (>99%) could be calculated for these devices.