Enhanced light harvesting of CdSe quantum dot sensitized bilayered ZnO nanostar/TiO2 nanotubes

► Bilayered ZnO/TiO2 nanotube was fabricated depending on the growth time of ZnO layer. ► ZnO layer consisting of star-shaped nanorods contributes to the enhanced photocurrent. ► CdSe quantum dots based photoelectrochemical cells were fabricated. ► The optimal condition resulted from ZnO growth for 2 h shows the efficiency of 0.94%.