Needle Profile Grating Structure for Absorption Enhancement in GaAs Thin Film Solar Cells

•Our calculation shows that the absorptivity of our proposed NP grating is over 20% higher than that of rectangular grating.•The optimized NP grating can absorb more than 90% of above-bandgap sunlight.•This NP structure can be thought as a promising solution for light absorption enhancement of thin film solar cells.

We conduct a systematic study of thin film solar cells consisting of a GaAs needle profile (NP) grating structure as a light-trapping layer. The influence of geometric parameters on the optical absorption of the NP grating is investigated using rigorous coupled wave analysis and the finite element method. This type of structure can lead to broadband optical absorption enhancement throughout the wavelength range that we studied. Our simulation results reveal that the absorption efficiency of NP grating can be improved significantly compared with its rectangular grating counterpart. The proposed structure is expected to illuminate the design and fabrication of high-efficiency solar cells.