The effect of various concentrations of PVDF-HFP polymer gel electrolyte for dye-sensitized solar cell.

A PVDF-HFP gel electrolytes based DSSCs were fabricated successfully, where gel electrolytes with 2.5 wt.%, 5 wt.%, 10 wt.% and 15 wt.% PVDF-HFP are included, respectively. Linear sweep voltammetry (LSV), photocurrent–voltage measurements and electrochemical impedance spectra (EIS) were measured. As the results shown, the apparent diffusion coefficient (D app ) of I − and I 3 − decreased as PVDF-HFP increased. D app of I − and I 3 − are decreased from 1.87 × 10 − 6 to 0.67 × 10 − 6 cm 2 /s and 3.28 × 10 − 6 to 0.88 × 10 − 6 cm 2 /s, respectively. For the solar cell measurements, the short circuit current density (J sc ) were affected by the ion motilities, which was decreased from 11.58 mA/cm 2 to 8.17 mA/cm 2 , and the energy converting efficiency (η %) was decreased from 5.17% to 2.79%. For electrochemical impedance spectra (EIS) measurements, the ionic diffusion impedance for the redox-couple (I − /I 3 − ) in the gel electrolyte was also increased with the concentration of PVDF-HFP from 0.61 Ω to 8.17 Ω. In the Bode Plots, the electron lifetime (τ e ) of the 2.5 wt.% and 5 wt.% PVDF-HFP electrolytes was increased from 40.52 ms to 48.48 ms and 41.29 ms, respectively. However, τ e was decreased in the concentrations of 10 wt.% and 15 wt.% PVDF-HFP, due to the ion motilities that were decreased by excessing PVDF-HFP polymer. For gel electrolyte, the cell of 2.5 wt.% PVDF-HFP exhibited a better J SC of 10.89 mA/cm 2 , a higher energy conversion efficiency (η) of 4.75%, a higher fill factor (FF) of 61.26%, and a smaller R of 1.06 Ω than the 15 wt.% PVDF-HFP based cell. [ABSTRACT FROM AUTHOR]