High-density vertically aligned ZnO rods with a multistage terrace structure and their improved solar cell efficiency

This work reports a solution-based approach to grow high-density vertically aligned ZnO rod arrays with a multistage terrace structure (HDVAMT) on An nanoparticle covered glass substrates. The solar cell performance of HDVAMT is 10 times better than that of the disordered ZnO due to the much higher short circuit current (J(sc)). This significant improvement of J(sc) is attributed to two factors: the vertically aligned structure, which provides smoother electron transport channels, and the high density of the rods with the multistage terrace structure, which provides a higher surface area for the dye adsorption. A tentative growth mechanism is proposed.