Study of the Influence of the I-Based Electrolyte Composition on the Photoconversion Properties of p-Type Dye-Sensitized Solar Cells

In the framework of the research on dye-sensitized solar cells of p-type (p-DSCs) the definition and optimization of the electrolyte have been a crucial aspect for the reach of the recent records of photo-conversion for these devices. At the basis of this progress there was the replacement of the redox shuttle of reference I 3 − /I − with opportune redox mediators which deliver higher photocurrents and produce larger open circuit photovoltages. In the present study we intend to optimize the composition of the iodine-based electrolyte for p-DSCs employing variable concentrations of redox shuttle. Beside the general conditioning of the overall performance, the analysis of the influence of p-DSC electrolytes has concerned the aspects of the extent of optical parasitic absorption of the electrolyte, of the chemical aggressiveness of the redox species and of the control of the phenomena of electronic back-donation by the photoreduction product. Non-obvious correlations have been found between the main cell parameters (η, J SC , V OC , FF) and the electrolyte conductivity. In the present work, a photocurrent density higher than 4.0 mA*cm −2 is reported when I-based electrolyte (LiI 1.0 M and I 2 1.0 M in ACN) was employed. EIS experiments proved that this outstanding photocurrent was due to the lowering of recombination phenomena.