High efficiency enhancement of multi-crystalline silicon solar cells with syringe-shaped ZnO nanorod antireflection layers

High performance antireflection (AR) coating is essential to the conversion efficiency (η) enhancement of PV devices. In this work, an AR structure based on syringe-shaped ZnO nanorod arrays was obtained by two-step aqueous solution method. The morphology of the syringe-shaped nanorods can be easily regulated by changing experiment parameters of each growth step. With this structure, the surface reflection of multi-crystalline silicon solar cell was effectively suppressed below 5% over a wide range of wavelengths. Meanwhile, the short-circuit current density and η of the solar cell were increased up to 34.98 mA/cm2 and 17.16%, enhancements of ~37% and ~41% from those on bare surface. These results are attributed to the ultrasharp tips on the tops of nanorods can make the effective refractive index gradual increasing from air to the bottom of ZnO nanorods, which leads to enhanced light trapping on the solar surface.