Efficiency Enhancement of a Single-Junction GaAs Solar Cell with ZnO Nanorod Arrays as an Antireflection Layer

Abstract

We report a 4.8% absolute efficiency enhancement for a single-junction GaAs solar cell fabricated with ZnO nanorod arrays (NRAs) as an antireflection (AR) layer. The efficiency enhancement, compared to a bare solar cell, mainly stems from the increase in current density due to AR effects caused by ZnO NRAs. The seed layer necessary for ZnO NR growth was deposited by RF magnetron sputtering without fill factor degradation, and ZnO NRAs of different lengths were subsequently fabricated by using the hydrothermal method. The reflectance, external quantum efficiency, and current density-voltage characteristics were measured for the fabricated GaAs solar cells. The reflectance measurement showed that the ultraviolet-to-near infrared reflectance was significantly suppressed for GaAs solar cells with ZnO NRAs. A GaAs solar cell with ZnO NRAs with lengths of 620 nm and a mean diameter of 30 nm shows the highest efficiency of 19.9%.