Mono-ion transport electrolyte based on ionic liquid polymer for all-solid-state dye-sensitized solar cells

Ionic liquid polymers, poly(1-alkyl-3-(acryloyloxy)hexylimidazolium iodide), are synthesized and used as mono-ion transport electrolytes for all-solid-state dye-sensitized solar cells. For these ionic liquid polymers, imidazolium cations are tethered on polymer main chain and only iodide species is mobile. Such a mono-ion transport feature is favorable as solid-state electrolyte in dye-sensitized solar cells. High thermal stability up to 200 C for these ionic liquid polymers is confirmed by thermogravimetric analysis. Among these ionic liquid polymers, poly(1-ethyl-3-(acryloyloxy)hexylimidazolium iodide) (PEI) exhibits the highest ionic conductivity (3.63 10 4 S cm 1) at room temperature. The dye-sensitized solar cell based on PEI electrolyte without the addition of iodine exhibits the open-circuit voltage of 838 mV, the short-circuit current density of 9.75 mA cm 2 and the conversion efficiency of 5.29%, measured at AM 1.5 illumination (100 mW cm 2). Incorporating iodine into PEI electrolyte results in the decrease of both the open-circuit voltage and the photocurrent density due to the visible light adsorption by iodine and the enhancement of the recombination between conduction band electrons and the triiodide. 2012 Elsevier Ltd. All rights reserved