Toward eco-friendly dye-sensitized solar cells: Developing chitosan-based electrolytes with conducting polymers and ionic liquids

Optimization of chitosan-based gel electrolytes modified with conducting polymers and ionic liquids for dye-sensitized solar cells (DSSC) has been done to improve its electrochemical activity. The effects of iodide salts, 1-propyl-3-methylimidazolium iodide (PMII), and polyaniline incorporation on the electrochemical properties of chitosan-based electrolyte, as well as its performance as a quasi-solid electrolyte in DSSC, were systematically investigated. A study on the effect of different iodide salts on the electrochemical properties of the electrolyte was conducted by employing various iodide salts (lithium iodide, sodium iodide, potassium iodide, or cesium iodide). Electrolytes with various amounts of PMII and polyaniline were also prepared. X-ray diffraction (XRD) and Fourier transform-infrared (FTIR) analysis were conducted to study the effect of iodide salts, PMII, and polyaniline on the change in intermolecular interaction of the chitosan matrix. The ionic conductivity and the redox activity of the chitosan-based electrolyte were respectively evaluated using conductometry and cyclic voltammetry analysis. It is found that the larger cation size of the iodide salts and a higher amount of PMII resulted in both higher intensity of the redox peak current and conductivity of the electrolyte. Those two characteristics increase with the presence of polyaniline, but the low transparency of this polyaniline-based electrolyte lowers the solar cell’s efficiency. The highest performance DSSC utilizing a chitosan/KI-PMII based electrolyte resulted in a Voc of 0.402 V, Jsc of 0.335 mA/cm², fill factor (FF) of 0.432, and an overall power conversion efficiency (PCE) of 0.058%. This efficiency is approximately one-third that of the conventional liquid electrolyte-based DSSC. The optimized chitosan-based electrolyte offers promising performance in replacing the low-stability liquid electrolyte-based DSSC.