Three-dimensional observation of TiO2 nanostructures by electron tomography

► We observed TiO2 nanostructures by TEM and electron tomography. ► We can observe entire shapes of TiO2 nanotubes from 3D reconstruction. ► Nanocylinder shapes of solar cells were also studied in this paper. Three-dimensional nanostructures of TiO2 related materials including nanotubes, electron acceptor materials in hybrid polymer solar cells, and working electrodes of dye sensitized solar cells (DSSCs) were visualized by electron tomography as well as TEM micrographs. The regions on the wall of TiO2 nanotubes where the streptavidins were attached were elucidated by electron tomogram analysis. The coverage of TiO2 nanotubes by streptavidin was also investigated. The TiO2 nanostructures in hybrid polymer solar cells made by sol–gel and atomic layer deposition (ALD) methods and the morphologies of pores between TiO2 particles in DSSCs were also observed by reconstructed three-dimensional images made by electron tomography.