Locally placed nanoscale gold islands film within a TiO₂ photoanode for enhanced plasmon light absorption in dye sensitized solar cells

As metal nanostructures demonstrated extraordinary plasmon resonance, their optical characteristics have widely been investigated in photo-electronic applications. However, there has been no clear demonstration on the location effect of plasmonic metal layer within the photoanode on both optical characteristics and photovoltaic performances. In this research, the gold (Au) nano-islands (NIs) film was embedded at different positions within the TiO₂ nanoparticulate photoanode in dye-sensitized solar cells (DSSC) to check the effect of plasmon resonance location on the device performance; at the top, in the middle, at the bottom of the TiO₂ photoanode, and also at all the three positions. The Au NIs were fabricated by annealing a Au thin film at 550 °C. The DSSC having the Au NIs-embedded TiO₂ photoanode exhibited an increase in short circuit currents (J_sc) and power conversion efficiency (PCE) owing to the plasmon resonance absorption. Thus, the PCE was increased from 5.92% (reference: only TiO₂ photoanode) to 6.52% when the Au NIs film was solely positioned at the bottom, in the middle or at the top of TiO₂ film. When the Au NIs films were placed at all the three positions, the J_sc was increased by 16% compared to the reference cell, and consequently the PCE was further increased to 7.01%.