Effects of different iodide salts on the electrical and electrochemical properties of hybrid biopolymer electrolytes for dye-sensitized solar cells application

Biopolymer hybrid electrolytes based on carboxymethyl kappa -carrageenan/carboxymethyl cellulose doped with various cation sizes of iodide salts were prepared using the solution casting method. Lithium iodide, sodium iodide, ammonium iodide, and N–N-Dimethyl-N-(methyl-sulfanylmethylene) ammonium iodide are the doping salts used in this work. The Fourier transform infrared spectra and thermal analysis of all four systems prove the occurrence of complexation between the host polymer and the iodide salts. Impedance study showed that the ionic conductivity increased with an increase in salt concentration. The highest ionic conductivities were 3.89 × 10 –3 S cm −1 , 4.55 × 10 –3 S cm −1 , 2.41 × 10 –3 S cm −1 and 6.68 × 10 –3 S cm −1 for biopolymer hybrid systems containing lithium iodide (30 wt%), sodium iodide (30 wt%), ammonium iodide (30 wt%) and N–N-Dimethyl-N-(methyl-sulfanylmethylene) ammonium iodide (40 wt%). The temperature-dependent conductivity study revealed that all of the carboxymethyl kappa -carrageenan/carboxymethyl cellulose hybrid-based electrolytes followed the Vogel-Tamman-Fulcher model conductivity-temperature behavior. The dye-sensitized solar cell fabricated (DSSC) with carboxymethyl kappa-carrageenan/carboxymethyl cellulose-40 wt% of N–N-Dimethyl-N-(methyl-sulfanylmethylene) ammonium iodide electrolyte showed good response under light intensity of 100 mW cm −2 and exhibited the highest efficiency of 0.21%, confirming that hybrid biopolymer systems can potentially be used for the fabrication of efficient DSSC.