The effects of polymer gel electrolyte composition on performance of quasi-solid-state dye-sensitized solar cells

Polymer gel electrolytes based on poly(acrylic acid)-poly(ethylene glycol) (PAA-PEG) hybrid have been prepared and applied to developed quasi-solid-state dye-sensitized solar cells (DSCs). PAA-PEG hybrid was synthesized by polymerization reaction. Quasi-solid-state DSCs were fabricated with synthesized PAA-PEG electrolyte. The effects of alkali iodides LiI, KI, and I₂ concentrations on liquid electrolyte absorbency and ionic conductivity of PAA-PEG were investigated. The evolution of the solar cell parameters with polymer gel electrolyte compositions was revealed. DSCs based on PAA-PEG with optimized KI/I₂ concentrations showed better performances than those with optimized LiI/I₂ concentrations. The electrochemical impedance spectroscopy technique was employed to examine the electron lifetime in the TiO₂ electrode and quantify charge transfer resistances at the TiO₂/dye/electrolyte interface and the counter electrode in the solar cells based on the PAA-PEG hybrid gels. A maximum conversion efficiency of 4.96% was obtained for DSCs using KI based quasi-solid electrolyte under 100 mW cm^-2. Our work suggests that KI can be the promising alkali metal iodide for improving the performance of PAA-PEG hybrid gel DSCs.