Effect of TiO 2 nanopatterns on the performance of hydrogenated amorphous silicon thin-film solar cells

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 (300nm in diameter) having a period of 500nm are formed onto AZO films and vary from 60 to 180nm in height. Haze factor increases with an increase in the height of the nanopatterns in the wavelength region below 530nm. 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 100nm, and then decreases. Measurements show that a-Si:H solar cells fabricated with 100nm-high TiO2 nanopatterns exhibit the highest conversion efficiency (6.34%) among the solar cells with the nanopatterns and flat AZO sample.