Electrochemical and structural characterization of polyacrylonitrile (PAN)–based gel polymer electrolytes blended with tetrabutylammonium iodide for possible application in dye-sensitized solar cells

Abstract

Polyacrylonitrile (PAN)–based gel polymer electrolytes (GPEs) consisting of plasticizers ethylene carbonate (EC) and propylene carbonate (PC) and different compositions of tetrabutylammonium iodide (TBAI) salt have been investigated. The GPEs have been characterized by electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSV), and X-ray diffraction (XRD) techniques. EIS study shows that the GPE containing 30 wt% TBAI has the lowest bulk impedance, Rb (23 Ω), and highest room temperature ionic conductivity (3.46 × 10−3 S cm−1). Conductivity-temperature relationship in the temperature range studied obeys Arrhenius rule. The Ea value is decreased with TBAI percentage and is the lowest (12.59 kJ/mol) for GPE containing 30 wt% TBAI. From LSV experimental data, the limiting current density (Jlim), apparent diffusion coefficient of triiodide ion ( $$ {D}_{I_3^{-}}^{\ast } $$ ), and exchange current density (J0) have been calculated. The highest value for each of these parameters is 5.00 mA cm−2, 6.59 × 10−7 cm2 s−1, and 0.63 mA cm−2, respectively, for the highest conducting GPE. All samples are amorphous. LSV at stainless steel showed that the electrochemical stability window is 2.2 V. The cyclic voltammetry (CV) was performed from 1 to 1000 cycle which showed good electrochemical stability.