Dye-sensitized solar cells based on amphiphilic composite electrolytes

Abstract

In this thesis, amphiphilic composite electrolytes for dye-sensitized solar cells are described. The PDA-based electrolyte systems afford both ion channels and solid state electrolytes. Jeffamine, a diamine terminated polyether, was used as ionic transporting matrix and diacetylene containing lipid was used as a supramolecular scaffold. The cell performance of the DSSC employing Jeffamine alone was found to be extremely low (i.e. overall energy conversion efficiency η = 0.03% at 100 mW/cm2) while the PDA-based electrolytes displayed increased cell performance (i.e., overall energy conversion efficiency η = 2.14% at 100mW/cm2). The increase of the cell efficiency is presumably due to the formation of ionic channel. Quazi-solid state electrolytes were also developed based on a physical mixing of oligoethylene oxide containing amphiphilic lipid (Brij 72) with PEGDME. Addition of small amount of Brij 72 to PEGDME not only changes its phase to quasi-solid state but it also increases the photocurrent. Comparison with pure PEGDME based electrolytes the Brij 72-PEGDME composite electrolyte has similar open circuit voltage but increased short circuit current (12.9 mA/cm2 at 100 mW/cm2). The increased in Jsc is presumably due to the hydrophobic property of Brij 72. This makes MPII easier to ionize and faster movement of the ions. The best efficiency of the DSSC employing the amphiphic PEG-PEGDME based electrolytes is 4.09% at 100 mW/cm2.