Characteristics of dye-sensitized solar cells (DSSCs) using liquid and gel polymer electrolytes with tetrapropylammonium salt

In this work, liquid electrolytes (LEs) and gel polymer electrolytes (GPEs) containing tetrapropylammonium iodide (TPAI) salt, propylene carbonate, ethylene carbonate, N,N-dimethylformamide and (I−/I3−) redox couple have been prepared. For GPEs, the additional material was poly(ethylene oxide). The impedance of these electrolytes was measured using electrochemical impedance spectroscopy to determine their ionic conductivity. Conductivity was found to increase with salt content in LEs whereas in GPEs, conductivity was initially enhanced but it was followed by decrement. The highest ionic conductivity for the GPE and LE were 2.53 mS cm−1 (0.20 g TPAI) and 8.98 mS cm−1 (0.25 g TPAI), respectively at room temperature. Dye-sensitized solar cells (DSSCs) were fabricated using all LEs and the highest conducting GPE. At 100 mW cm−2 illumination, DSSC with LE exhibited the efficiency of 6.61% with short circuit current density, Jsc= 18.69 mA cm−2, open circuit voltage, Voc = 0.68 V and fill factor, FF = 0.52 whereas DSSC using GPE delivered the efficiency of 3.29% with Jsc= 11.78 mA cm−2, Voc = 0.65 V, FF = 0.43. The highest incident photon conversion efficiency (IPCE) at 520 nm is 45.5% for DSSC with 0.25 g TPAI LE and 41.1% for DSSC with GPE at the same wavelength.