FDTD analysis of the optical properties of vertical ZnO nanorod array

Based on the structure and dimensions of a vertical ZnO nanorod array (V-ZNA) sample, an ideal 2-D photonic crystal model was established. The optical properties of the V-ZNAs were analyzed with finite-difference time-domain (FDTD) method, and the influences of the geometry parameters, including the circumcircle diameters of the top and bottom surfaces (D _t and D _b) and the height (H) of the nanorods, and the pitch between each column (L), were discussed. High transmittance and low reflectance in the waveband of 400–800 nm were proved, and the highest transmittance can be obtained with D _t<50 nm, H=200 nm, and D _b/L=0.85, which was verified by Effective Index Method (EIM). The result indicates that V-ZNAs can be used as excellent light coupling element and antireflection material for solar energy applications.