Synthesis of a series of novel imidazolium-containing ionic liquid copolymers for dye-sensitized solar cells

A series of imidazolium-containing ionic liquid copolymers has been synthesized through free radical co-polymerizations of an imidazolium-containing ionic liquid monomer (MEBIm-I), poly(ethylene glycol) methyl ether methacrylate (POEM), and acrylonitrile at various molar ratios. A thorough investigation has been conducted to study the effects of the chemical structure on the ionic conductivities, ionic diffusion coefficients, and catalytic activities of the ionic liquid copolymers. The presence of the ethylene oxide segments enhanced the ionic diffusion coefficients and conductivities of the POEM-containing ionic liquid copolymers. The incorporation of suitable contents of acrylonitrile units enhanced the catalytic activities of the ionic liquid copolymers. The photovoltaic and electrochemical impedance properties of dye-sensitized solar cells (DSSCs) assembled from these ionic liquid copolymer-based electrolytes have been evaluated. A maximum power conversion efficiency of 7.57%, with a maximum short-circuit current density of 16.0 mA cm(-2), an open-circuit voltage of 0.84 mV, and a fill factor of 57.0%, has been achieved for DSSCs based on the ionic liquid copolymers (architecture: fluorine-doped tin oxide (FTO) glass/TiO2/N719 dye/ionic liquid polymer-based electrolyte/Pt/FTO glass) under AM 1.5 illumination with an intensity of 100 mW cm(-2).