Solar cell, One-dimensional nanostructure, Surface reflectance, Plane-wave expansion Abstract. In this paper, we design a one-dimensional (1-D) a-Si nanostructure, orthogonizing the two processes to avoid their competition. Shapes of the structure include 1-D nanowire and 1-D nanocone. With the method of plane-wave expansion, the influence of different parameters on surface reflectance is systematically discussed. It is verified that, under the given geometrical parameters, 1-D nanocone solar cell will perform better than 1-D nanowire one and flat one in optical absorption enhancement.