Enhancing photovoltaic performance of all-solid-state dye-sensitized solar cells by incorporating ionic liquid-physisorbed MWCNT

Multi-walled carbon nanotubes (MWCNT) coated with a thin layer of 1-(2-acryloyloxy-ethyl)-3-methyl-benzoimidazol-1-ium iodide were successfully fabricated by physical adsorption. They were then incorporated into poly(1-(2-acryloyloxy-ethyl)-3-methyl-imidazol-1-ium iodide (poly(AMImI))-based electrolytes to create an all-solid state dye-sensitized solar cell (DSSC). The power conversion efficiency (PCE) of the resulting DSSC was significantly increased, higher than that using poly(AMImI)-grafted MWCNT incorporated in the poly(AMImI)-based electrolytes. With gradual increases in the 1-(2-acryloyloxy-ethyl)-3-methyl-benzoimidazol-1-ium iodide-physisorbed MWCNT content from 0 to 0.5 wt%, the PCE increased from 1.156 to 3.551% at full sun and the short-circuit current density (J(SC)) increased from 2.367 to 8.505 mA cm(-2). According to the linear sweep voltammetry measurements, the presence of 1-(2-acryloyloxy-ethyl)-3-methyl-benzoimidazol-1-ium iodide-physisorbed MWCNT in the solid-state electrolytes significantly increased the limiting current and the diffusion coefficient of I3(-). Notably, the relationship between the JSC and the increase of limiting current with the content of 1-(2-acryloyloxy-ethyl)-3-methyl-benzoimidazol-1-ium iodide-physisorbed MWCNT is linear.