Fabrication and Properties of Dye-Sensitized Solar Cells with Screen-Printed Bilayer Composite Film Photoactive Electrode

Abstract

To enhance the conversion efficiency of dye-sensitized solar cells (DSSCs), a novel photoactive electrode based on the bilayer composite films consisting of titanium dioxide/carbon nanotubes (TiO₂/CNTs) mixed film and pure TiO₂ film are fabricated on ITO coated glass. The TiO₂/CNTs mixed underlayer was used to reduce the internal resistance of charge transport within photoactive layer, which would enhance short circuit photocurrent density, and the pure TiO₂ overlayer was employed to prevent indirect charge recombination between ITO electrode and redox electrolyte. Scanning electron micrographs show that the spherical TiO₂ nanoparticles were homogenously distributed, and the CNTs geometrically matched with the TiO₂ nanoparticles by filling into the interspaces within mesoporous bilayer composite films. Electrochemical impedance spectra (EIS) reveal that the bilayer composite films could decrease the internal resistance of charge transport within photoactive layer. Incident photon to current conversion efficiency (IPCE) measurement results reveal that the bilayer composite films could improve the photocurrent for the DSSC in near-infrared region from 600 nm to 800 nm.The photocurrent voltage measure shows that the composite bilayer film could enhance the short circuit photocurrent density of the DSSC from 9.11 mA·cm⁻² to 12.67 mA·cm⁻², and the overall conversion efficiency from 2.94% to 5.08%.

Keywords:

• Dye-sensitized
• carbon nanotube
• conversion efficiency
• solar cell