A novel low aspect-ratio Si nano-hemisphere surface texturing scheme for ultrathin film solar cells

Low aspect-ratio Si nano-hemisphere array surface texturing compatible to ultrathin film solar cells is proposed and experimentally studied for both optical and electrical performance improvements. Light reflection can be significantly suppressed through rationally designed nano-hemisphere array surface texturing, thanks to the spatial effective refractive index (n_eff) modulation. Owing to the excellent light trapping and also to the nature of low aspect ratio (critical for conformal deposition of electrodes and achieving low surface defects), a record-high short circuit current density (J_sc) of 37.4 mA/cm² among all published Si nano-structured solar cells is achieved, in distinct comparison with J_sc of 20.7mA/cm² measured from the reference flat solar cells.