Branched open-ended TiO2 nanotubes for improved efficiency of flexible dye-sensitized solar cells

The anatase branched open-ended titanium dioxide (TiO 2 ) nanotubes (NTs) are prepared using a combined method of electrospinning, hydrothermal processing and calcination . The branched open-ended TiO 2 NT (BOTNT) is composed a trunk of a large sized NT, from which out growth many branches consisting of single-crystalline TiO 2 nanosheets (NSs) and small NTs. The morphology and microstructure of the BOTNTs can be controlled by varying with the hydrothermal treatment time. When it is used in flexible dye-sensitized solar cells (FDSSCs) as multifunctional layer covering on the carbon nanotubes (CNTs) incorporated TiO 2 (CNTs/TiO 2 ) nanorods (NRs) layer, a high conversion efficiency of 4.70% is obtained. This efficiency is much higher than that of the cell assembled by the single-layer CNTs/TiO 2 NRs film. This is attributed to the great increase in light harvesting efficiency , resulting from excellent light-scattering ability and high specific surface area for dye loading of the BOTNTs. Furthermore, the excellent electron transport ability of the BOTNTs due to their high level of interconnectivity , improves the performance of FDSSCs.