Effect of polyaniline (PANI) on efficiency enhancement of dye-sensitized solar cells fabricated with poly(ethylene oxide)-based gel polymer electrolytes

Ionically conducting gel polymer electrolytes can be used effectively to improve the problems associated with liquid electrolytes in dye-sensitized solar cells (DSSCs) and in particular to reduce their electrode degradation. In this work, gel polymer electrolytes containing poly(ethylene oxide) (PEO), LiI, and I2 were used as the redox electrolyte and conducting polymer; polyaniline (PANI) as an additive was introduced to the PEO-based electrolytes. The effect of incorporating PANI into the PEO-based gel electrolyte on iodide ion conductivity and solar cell performance was studied. The gel polymer electrolyte without PANI showed a conductivity of 1.23 × 10−3 S cm−1 at room temperature, while the electrolyte incorporating 1.5 wt% PANI showed an enhancement in conductivity increasing its value up to 1.87 × 10−3 S cm−1. While the DSSCs fabricated without PANI in the electrolyte showed 5.00% efficiency, the DSSCs fabricated with 1.5 wt% PANI-incorporated polymer electrolyte showed 6.56% efficiency under the same illumination of 100 mW cm−2(AM 1.5) simulated sunlight. Ionic conductivity and FTIR results suggest that the increase in electrolyte conductivity and the enhancement of DSSC performance appear to be due to the combined result of the plasticizing effect on decreasing the crystallinity of the PEO polymer and the improved ionic dissociation due to “trapping” and immobilizing the Li+ cations in the polymer matrix by PANI, creating more iodide (I−) ions in the redox medium.