Plasmonic enhanced dye-sensitized solar cells with self-assembly gold-TiO2@core–shell nanoislands

• Synthesis of self-assembly gold-TiO2@core–shell nanoislands on TiO2 photoanode.
• Optical extinction and Raman spectroscopy shows plasmonic effect of the core–shell nanostructure.
• Morphological characterization shows the core–shell nanostructure on both TiO2 photoanode and counter-electrode.
• Photocurrent density–voltage (JV) measurement agrees with incident photon to charge carrier efficiency (IPCE).
• Our plasmonic enhanced dye-sensitized solar cell show improved photovoltaic performance.

Decorating TiO2 photoanode of dye-sensitized solar cell (DSSC) with silver or gold nanoparticles has been shown to be an effective approach for enhancing device performance via the plasmonic effects. Here, we show for the first time that the same approach can be adopted simultaneously for both the photoanode and the counter-electrode of a DSSC but operates with different enhancement mechanism. In this work, the plasmonic nanostructure is synthesized by physical vapor deposition of ultra-thin gold films onto the electrodes followed by thermal annealing at a recommended TiO2 sintering temperature to form self-assembly gold nanoislands. Protective TiO2 nanoshells were formed by hydrolysis of titanium isopropoxide (TIP) precursor over the gold nanoislands. By varying the initial gold film thickness, gold nanoislands of controllable dimensions are distributed uniformly over the electrode surfaces. It was found that the optimized core–shell nanoislands nearly doubles the short circuit photocurrent density from 9.4 mA/cm2 to 17.5 mA/cm2, and has little impact on the open circuit voltage, resulting in a substantial uplift of the energy conversion efficiency.