Ken-Yen Liu

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 (JSC) 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.

Gelation of ionic liquid with exfoliated montmorillonite nanoplatelets and its application for quasi-solid-state dye-sensitized solar cells.

The exfoliated montmorillonite (exMMT) nanoplatelets that carry negative charges are capable of adsorbing 1-methyl-3-propyl-imidazolium cations to form a gel-type ionic liquid-based electrolyte system for dye-sensitized solar cell (DSSC). Interestingly, it also increases the power conversion efficiency of DSSC from 6.58% to 7.77% at full sun. The increased efficiency is attributed to the decreased resistance of gel electrolyte system and enhanced reduction reaction rate at the counter electrode, both of which are related to the two-dimensional electrolyte nature of exMMTs that repel the I(-)/I(3)(-) redox couples toward their major conduction pathway.