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 (1.7×10 8   M −1  s −1 ) is very close to the maximum theoretical rate constant of 3.3×10 8   M −1  s −1 . Consequently, a very high dye‐regeneration yield (>99 %) could be calculated for these devices.