Palm-based polyurethane-ionic liquid gel polymer electrolyte for quasi-solid state dye sensitized solar cell

Abstract

In this study, the effect of palm-based polyurethane (PU) gel polymer electrolytes with the addition of 1-methyl-3-propylimidazolium iodide (MPII) on quasi-solid state dye sensitized solar cell (DSSC) was investigated. The PU was synthesized prior via pre-polymerization technique under nitrogen atmosphere. Different weight percentage of MPII ranging from 10 to 30 wt.% were added in PU solution to form a gel-polymer electrolyte. The chemical interactions of electrolytes were examined using Fourier transform infra-red spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Meanwhile, the ionic conductivities of electrolytes and photovoltaic characteristics of quasi-solid state DSSC were investigated by electrochemical impedance spectroscopy (EIS) and current-voltage (IV) measurements. FTIR spectrum proved there were interactions between PU and MPII at NH stretching, NH bending and CO stretching. The highest ionic conductivity values achieved were 9.07 × 10−4 S cm−1 for PU–25 wt.% MPII system. These results were supported by the decrement of the glass transition temperature (Tg) upon the addition of MPII which has also been proven by DSC results. The thermal stability measured by TGA also indicated that there were interactions which occurred between PU and MPII, correlated with the increment of ionic conductivities. The current-voltage characteristics of fabricated quasi-solid state DSSC (FTO/TiO2-dye/PU-MPII-I2/Pt at 25 wt.% MPII) demonstrated highest power conversion efficiency of 1.00% under a standard AM 1.5G illumination. These promising results could be a first step toward a new generation of low-cost and effective quasi-solid state DSSC from bio-based polymer electrolytes.