Optimization of photoelectrode by structural engineering for efficiency improvement of dye-sensitized solar cells at different light intensity

Abstract

Abstract Titanium (Ti) is a promising choice as the photoelectrode substrate of dye-sensitized solar cells (DSSCs) due to its high compatibility and stability. To enhance the efficacy of Ti more than a substrate, structural modification of Ti via anodization is performed to construct a TiO2 nanotube structure on the surface. Optimization of the TiO2 nanotube structure as a function of anodization potential is carried out in conjunction with the photovoltaic characterization of DSSCs using commercial N719 dye and synthesized organic D-Dye as the sensitizer. The highly oriented TiO2 nanotube structure not only increases the interactive contact area in between the Ti substrate and active semiconductor layer composed of TiO2 nanoparticles but also serves as a fast pathway for charge transfer and an additional channel to carry sensitizers, thereby greatly improving the cell efficiency. Maximum efficiency of 7.67% (Jsc of 16.06 mA/cm2, Voc of 0.693 V, and FF of 0.689) is achieved for the cell constructed by anodized Ti photoelectrode using N719 dye under 1 sun illumination. Incorporation of D-Dye further enhances the cell efficiency to 7.93% (Jsc of 16.65 mA/cm2, Voc of 0.701 V, and FF of 0.68) and this is attributed to the spatial effect of D-Dye molecules which have a long wingspan capable of suppressing the molecular aggregation. Under low light illuminations, maximum efficiency of 15.31% and 18.06% are reached for the cells constructed by anodized Ti photoelectrode using D-Dye under 3000 and 6000 lx illumination, respectively.