Cu@C nanoparticles dispersed RTILs used in the DSSC electrolyte

To enhance efficiency of a dye-sensitized solar cell (DSSC), a very small amount of Cu@C nanoparticles (prepared by carbonization of Cu2+–starch complexes at 573 K) is dispersed in room temperature ionic liquids (RTILs) (i.e., [bmim][BF4] and [bmim][PF6]), which is used as an electrolyte of the DSSC. By XRD and TEM, it is found that the Cu@C nanoparticles having Cu diameters of 7 and 18 nm are coated with a carbon shell (3–5 nm in thickness). Experimentally, the electrical conductivity of the RTILs dispersed with 0.1% of the Cu@C nanoparticles is increased by 8–15% in comparison with the plain RTIL. The X-ray absorption near edge structure (XANES) spectra of copper show that about 7% of Cu in the Cu@C nanoparticles dispersed RTILs are oxidized to CuO or Cu2O. The simulated solar efficiency of the DSSC utilizing the Cu@C nanoparticles dispersed RTIL electrolyte can be increased as high as 60%.