Dye-sensitized solar cells with PVA–KI–EC–PC gel electrolytes

Abstract

Gel polymer electrolytes consisting of PVA–EC–PC–KI have been studied in this work. The highest room temperature (298 K) conductivity of 12.92 mS cm$^{-1}$ is obtained for PVA-based gel polymer electrolyte (GPE) with composition 14.5 PVA-21.7 EC-28.7 PC-30.4 KI-4.7 $\text{ I }_{2}$ (in wt%). The high conductivity is due to the highest number density of mobile ions in the electrolyte. The conductivity–temperature dependence follows the Vogel–Tamman–Fulcher (VTF) relationship. The trend of pseudoactivation energy $(E_{a})$ with salt concentration is contrary to that of conductivity. PVA-based GPEs with 5 to 35 wt% KI were used as a medium in ruthenium 535 (N719) dye-sensitized solar cells. The efficiency ($\eta$) of the solar cells increased as the composition of KI salt in the electrolyte increased. The highest power conversion efficiency of 2.74 % is obtained for solar cells fabricated with electrolyte containing 35 wt% KI. The variation of efficiency follows the same trend as short circuit current density $(J_{sc})$. The increase in $J_{sc}$ is influenced by the increase in iodide ion concentration in the electrolyte that assists the redox process and helps electron to shuttle between ionized dye and counter electrode.