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. Dapp of I- and I-3(-) are decreased from 1.87 x 10(-6) to 0.67 x 10(-6) cm(2)/s and 3.28 x 10(-6) to 0.88 x 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 (eta %) 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 Omega to 8.17 Omega. In the Bode plots, the electron lifetime (tau(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, tau(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 Jsc of 10.89 mA/cm(2), a higher energy conversion efficiency (eta) of 4.75%, a higher fill factor (FF) of 61.26%, and a smaller R of 1.06 Omega than the 15 wt.% PVDF-HFP based cell. (C) 2015 Elsevier Ltd. All rights reserved.