Novel development towards preparation of highly efficient ionic liquid based co-polymer electrolytes and its application in dye-sensitized solar cells

Abstract

Ionic liquid polymer electrolytes (ILPE) were prepared with poly(1-vinylpyrrolidone-co-vinylacetate) P(VP-co-VAc) copolymer, tetrahexylammonium iodide (THAI) salt and 1-butyl-3-methylimidazolium iodide (BMII), a room temperature ionic liquid (RTIL). The ILPEs were characterized using electrochemical impedance spectroscopy (EIS) analysis, X-ray diffraction (XRD) studies, Fourier transform infrared spectroscopy (FTIR) and Thermogravimetric analysis (TGA). The highest ionic conductivity obtained was 1.05 × 10−3 S cm−1 at room temperature in ILPE3 which is the sample incorporated with 80 wt% of BMII. FTIR analysis proved the formation of complexes in between the copolymer, salt and ionic liquid. XRD studies have shown that ILPE3 has the optimum amorphous nature. The ILPE based dye sensitized solar cell (DSSC) was assembled by sandwiching the ILPE in between the nanoporous TiO2 working electrode and Pt-coated counter electrode and thus subjected to device photovoltaic characterization. The DSSC with ILPE3 as its electrolyte has shown the highest power conversion efficiency (η) with a value of 4.93% with short circuit current density (Jsc), open circuit voltage (Voc) and fill factor (FF) of 12.37 mA cm−2, 0.69 V and 0.58, respectively. Temperature dependence studies has been done on the DSSCs to understand effect of the cell temperature on the performances of the DSSCs. EIS studies of the DSSCs shows that the ILPE is having higher diffusion coefficient compared to the GPE.