ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY FOR STUDYING DSSC ELECTROLYTES
Keywords:
Keywords: DSSC; electrolyte; electrochemical impedance spectroscopy; Nyquist plot; Bode plot; gel polymer electrolyte; iodide/triiodide; diffusion impedance; constant phase element; Kramers-Kronig validation Nomenclature:Abstract
Abstract. Dye-sensitized solar cells (DSSCs) rely critically on the electrolyte to
regenerate the dye, transport redox species, and sustain charge-transfer at the counter
electrode while limiting recombination at the photoanode interface. Electrochemical
impedance spectroscopy (EIS) is one of the most informative nondestructive methods
for separating bulk electrolyte transport from interfacial kinetics and
diffusioncontrolled processes across a broad frequency window. This review
consolidates the theoretical basis of impedance spectroscopy in forms directly usable
for DSSC electrolyte research, with emphasis on Nyquist/Bode interpretation,
constant-phase behavior, diffusion impedance, and the relationship between fitted
parameters and physically meaningful electrolyte properties such as ionic conductivity,
effective permittivity, diffusion coefficient, mobility, and charge-carrier concentration.
We provide a rigorous and practical workflow for designing EIS experiments in
symmetric "dummy" cells and complete DSSCs under dark and illumination, highlight
pitfalls related to non-stationarity and model non-uniqueness, and describe validation
using Kramers-Kronig consistency tests. Representative electrolyte formulations-
including iodide/triiodide liquid electrolyte and gel polymer electrolytes based on
PAN/EC/PC with iodide salts and ionic-liquid iodides, as well as polymer blends such
as PVP/PMMA-are discussed to illustrate how composition and morphology impact
impedance signatures. The review closes with reporting recommendations aimed at
improving reproducibility and comparability across studies, enabling EIS-guided
electrolyte optimization toward higher efficiency and improved stability DSSCs [1,2].
References
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