Polyacrylonitrile-based gel polymer electrolytes for dye-sensitized solar cells: a review

Dye-sensitized solar cell (DSSC) which was first introduced by Gratzel and co-workers 29 years ago is very attractive as the next generation sustainable energy device owing to its unique features such as inexpensive, flexibility, eco-friendly, simplicity in fabrication, functional at both indoors and outdoors, and so on. The heart of DSSC is the electrolyte which contains a redox mediator (e.g., I−/I3−). Conventional electrolyte used in DSSC is an organic liquid with the redox couple dissolved in it. Liquid electrolytes have high ionic conductivity but they suffer from leakage and electrochemical corrosion that affect the stability and consequently the cell performance. These have prompted researchers to employ polymer electrolytes particularly in gel form. Many gel polymer electrolytes (GPEs) have been developed but in this article, we pay special tribute to GPEs based on polyacrylonitrile (PAN) due to its high ambient conductivity, good mechanical integrity, and electrochemical stability with good performance.