The Effect of Physical Parameters on the Optical Properties of Type II Core-Shell ZnO/ZnTe Micropillar Solar Cells

This paper presents a study on the effects of the physical parameters (height, pitch and diameter) of the micropillar on the optical performance of type-II core-shell ZnO/ZnTe micropillar solar cell. The optical performance (absorption, transmission, reflection) of 3-D periodic cylindrical pillar structured ZnO/ZnTe solar cell has been analyzed using Lumerical FDTD solver. Micropillar solar cells are of two types (axial and radial) in terms of the formation of the p-n junction. Comparison of the optical performance between ZnO/ZnTe micropillars and conventional ZnO/ZnTe solar cell has been conducted. The results reveal an increase of light absorption at higher-wavelength regime and a significant reduction in light reflection over the entire wavelength regime for the type-II core-shell (radial) ZnO/ZnTe micropillar solar cell. The effect of the physical parameters (height, pitch, and diameter) of the type –II core shell ZnO/ZnTe micropillar on the optical performance of the device has been further studied. Pillar height of 4 μm results in highest degree of absorption (> 80%). As for the pitch, we observe a non-monotonic response. The optimum zone has been identified as 0.2 μm < pitch < 0.6 μm. A shell thickness of 70 nm leads to highest level of absorption within the lower wavelength (< 500 nm) of the relevant spectrum.