We investigate how TiO2 nanopatterns formed onto ZnO:Al (AZO) films affect the performance of hydrogenated amorphous silicon (a-Si: H) solar cells. Scanning electron microscopy results show that the dome-shaped TiO2 nanopatterns (300 nm in diameter) having a period of 500 nm are formed onto AZO films and vary from 60 to 180 nm in height. Haze factor increases with an increase in the height of the nanopatterns in the wavelength region below 530 nm. Short circuit current density also increases with an increase in the height of the nanopatterns. As the nanopatterns increases in height, the fill factor of the cells slightly increases, reaches maximum (0.64) at 100 nm, and then decreases. Measurements show that a-Si: H solar cells fabricated with 100 nm-high TiO2 nanopatterns exhibit the highest conversion efficiency (6.34%) among the solar cells with the nanopatterns and flat AZO sample. (C) 2012 Elsevier B. V. All rights reserved.