Significant enhancement of the performance of dye-sensitized solar cells with photoelectrode co-doped graphene and hybrid SiO<sub>2</sub>@Au nanostructure

Abstract

Attributed to facile fabrication, low production costs and outstanding photoelectric properties, dye-sensitized solar cells (DSCs) have attracted widespread attention in recent years. In order to achieve better photoelectric conversion efficiency of the DSCs, a series of TiO<sub>2</sub> nanocomposite photoanodes co-doped with different amounts of hybrid SiO<sub>2</sub>@Au nanostructures and certain amount of graphene are prepared by a mechanical ball milling method. The influence of SiO<sub>2</sub>@Au nanostructures and graphene on the performance of the photoanodes and their DSCs were investigated. The Au nanoparticles can remarkably enhance the short-circuit current density (<i>J</i><sub>sc</sub><italic/>) due to the local surface plasmon resonance effect of the noble metal nanoparticles. As a unique two-dimensional material, graphene has several amazing characteristics, such as high specific surface area and excellent conductivity. Studies showed that by introducing both SiO<sub>2</sub>@Au nanostructures and graphene, the light-absorbing, electron mobility and dye loading of the photoanodes were remarkably increased. Experimental results indicated that in comparison with those DSCs based with pure TiO<sub>2</sub> photoanode, the DSCs with photoanodes incorporated with SiO<sub>2</sub>@Au nanostructures and graphene showed the optimal performance with short-circuit current density (<i>J</i><sub>sc</sub><italic/>) of 15.59 mA/cm<sup>2</sup> and photoelectric conversion efficiency (PCE) of 6.68%, increasing significantly by 15.67% and 8.8%, respectively. This significant enhancement in <i>J</i><sub>sc</sub><italic/> and PCE of DSCs are mainly attributed to the increase in light-absorption and dye-loading of the photoanodes due to the hybrid SiO<sub>2</sub>@Au nanostructures and graphene.