A novel TiO2 nanorod/nanoparticle composite architecture to improve the performance of dye-sensitized solar cells

In this article, we first prove that the length increase of TiO2 nanorods by extending reaction time is infeasible for improving dye-sensitized solar cells (DSSCs) efficiency because the longer growth time will lead to combination of nanorods from the roots part and formation of dense film. Then a TiO2 nanorod-nanoparticle mesoporous film composite anode structure is designed and fabricated that serves as a model architecture for efficient cell devices as it simultaneously offers a large surface area, good light-scattering characteristics and a highly conductive pathway for charge carrier collection. Under standard solar cell measurement conditions, a photovoltaic conversion efficiency of 2.51% is obtained from the nanorod-nanoparticle film composite structure, which is higher than that of pure TiO2 nanorods DSSC (1.11%). By another surface treatment process with TiCl4, the DSSC efficiency based on such composite TiO2 anode is further improved to 3.25%.