Application of the tris(acetylacetonato)iron(III)/(II) redox couple in p-type dye-sensitized solar cells

Abstract

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 (JSC=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 VOC=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 (1.7×108 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.