A Novel Gel Electrolyte Based on Polyurethane for Highly Efficient in Dye-sensitized Solar Cells

A structurally interconnected block copolymer was facilely prepared by the polymerization of poly(oxyethylene)-segmented diol (PEG2000 and PPG1000) and Isophorone diisocyanate (IPDI), followed by a late-stage curing to generate urethane group cross-linked gels. The gel structure, with multiple functionalities including poly(oxyethylene) segments and urethane linkers were characterized by Fourier transform infrared spectroscopy. The gel-like copolymer was used to absorb a liquid electrolyte; formation of 3D interconnected nanochannels, as could be observed by field emission scanning electronic microscopy has confirmed this absorption of the liquid electrolyte by the copolymer. This elastomeric copolymer was used as the matrix of a polymer gel electrolyte (PGE) for a dye-sensitized solar cell (DSSC), which shows extremely high photovoltaic performance (soaking for 1 h in the electrolyte). In particular, the PGE containing 65 wt% of the liquid electrolyte renders a power conversion efficiency of 7.68 % for its DSSC, with a short-circuit photocurrent density of 16 mA cm^?2, an open-circuit voltage of 0.73 V, and a fill factor of 0.65. Electrochemical impedance spectra, and dark current measurements were used to substantiate the explanations of the photovoltaic parameters.