Functional quasi-solid-state electrolytes for dye sensitized solar cells prepared by amine alkylation reactions

Abstract

Novel quasi-solid state electrolytes for dye-sensitized solar cells (QSS-DSCs) are prepared by the amine alkylation reaction. In particular two oligomers of poly(propylene oxide) and one block oligomer of poly(ethylene oxide)/poly(propylene oxide) with two amino groups grafted at both edges of the oligomers were used as amine sources with iodoethane as the alkyl halide for substitution reactions. The nucleophilic aliphatic substitution (of the halide) reaction gives a higher substituted amine product and an iodide ion which is essential for QSS-DSC operation. Fourier transform infrared and UV-Vis spectroscopy, differential scanning calorimetry as well as electrochemical impedance spectroscopy were employed to characterize the resulting material after the alkylation reaction. The sequential quasi-solid state electrolytes only containing the new quasi-solid materials after mixing amino ended oligomers with iodoethane and iodine without any plasticizer and additional iodide sources were examined as gel electrolytes in QSS-DSCs consisting of thin and transparent TiO₂ photoelectrodes sensitized with a N-719 ruthenium complex. The cells were found to be durable to thermal and light soaking exposure while a maximum overall efficiency of 3.7% was recorded without the presence of any solvent or additive for voltage and current enhancement.