Abstract

Nanostructured photoanode material is one of key parts of dye (or quantum dot)-sensitized solar cells (DSSCs or QDSSCs). Although highly efficient power conversion efficiency has been achieved for DSSCs by using TiO₂ nanoparticle photoelectrode, there is immense interests to develop novel hierarchical nanostructured materials which serve to improve the photovoltaic performance. Here we report a series of hierarchical wide band gap semiconductor photoanode materials (TiO₂, ZnO, SnO₂ and Zn₂SnO₄) prepared via simple sonochemical or hydrothermal process, which show superior photovoltaic performance comparing to the corresponding nanoparticle. Hierarchical TiO₂ microsphere, anatase TiO₂ nanowire arrays, ZnO hollow spheres, SnO₂ octahedra, and marcoporous Zn₂SnO₄ have been synthesized and as very promising photoelectrodes for DSSCs or QDSSCs. Specially, hierarchical TiO₂ microsphere consisting of anatase TiO₂ nanorods and nanoparticle shows a power conversion efficiency of 10.34 % accompanying with 18.78 mA cm^-2 in J_sc, 826 mV in V_oc. These photovoltaic parameters are much higher than those of P25 nanoparticle, which are mainly attributed to considerable surface area (63.73 vs 59.89 m² g^-1 for P25 nanoparticles), a higher light scattering ability (reflectance: about 60 % at a range from 400 nm to 800 nm) and faster electron transport rate and slower recombination rate for this novel hierarchical TiO₂ microsphere. In addition, the QDSSCs based on hierarchical TiO₂ microsphere photoelectrode combining with the electrodeposited CdS/CdSe quantum dots showed 4.81 % photovoltaic performance.

© 2013 Optical Society of America