Conical-shaped titania nanotubes for optimized light management in DSSCs reach back-side illumination efficiencies > 8%
In the present work, we introduce the anodic growth of conical shaped TiO2 nanotube arrays. These titania nanocones provide a scaffold for dye-sensitized solar cell (DSSC) structures with significantly improved photon management, providing an optimized absorption profile compared with conventional cylindrical nanotube arrays. Finite difference time domain (FDTD) modelling demonstrates a drastically changed power-absorption characteristic over the tube length. When used in a back-side illumination DSSC configuration, nanocone structures can reach over 60% higher solar cell conversion efficiency (η) than conventional tubes. The resulting η ≈ 8% represents one of the highest reported values for Grätzel type DSSCs used under back-side illumination.