Novel agarose gel electrolytes are prepared by allylimidazolium iodides-based ionic liquids and environmentally benign co-solvents (propylene carbonate (PC) and dimethyl sulfoxide (DMSO)) for dye-sensitized solar cells (DSSCs). Among 1-allyl-3-ethylimidadolium iodide (AEII), 1-allyl-3-propylimidazolium iodide (APII), 1-3-diallylimidazolium iodide (DAM, and 1-methyl-3-propylimidazolium iodide (MPII) ionic liquids, the agarose gel electrolyte containing AEII exhibits the best DSSC performance. The efficiency of the DSSC using the agarose gel electrolyte containing 1.5 M AEII and 0.65 wt% agarose is 5.89% with the highest I-3(-) diffusion coefficient of 7.7 x 10(-6) cm(2) s(-1). The performance of the AEII ionic liquid-based agarose gel electrolyte is comparable to the liquid electrolyte based on 3-methoxypropionitrile (MPN) (5.84%) under illumination at AM 1.5, 100 mW cm(-2). Moreover, the DSSC performance of the allylimidazolium iodides ionic liquid-based agarose electrolyte is determined by the interaction between ionic liquid and agarose, which affects the rigidity of the ion channels and the I-3(-) diffusion coefficient. (C) 2013 Elsevier Ltd. All rights reserved.