ZnO Nanorods as Antireflection Layers in Metal-Insulator-Semiconductor Solar Cells

Abstract

One of the most promising techniques for manufacturing low-cost solar cells is a solution processing method. In this study, it is proposed that solution-grown ZnO nanorods (NRs) are used as antireflection coatings on metal-insulator-semiconductor (MIS) solar cells with sol-gel SiO2. Except Al electrodes prepared by thermal evaporation, no other vacuum process was utilized during fabrication. The ZnO NRs were produced with a hydrothermal method and suppressed Fresnel reflection. With the solution-grown ZnO NRs, it was observed the average reflectance of the MIS solar cell decreased from 38.7% to 15.8%, and the short circuit density (JSC) increased from 5.22 mA/cm2 to 6.71 mA/cm2 (28.4% enhancement). Meanwhile, the open circuit voltage (VOC) was improved from 0.39 V to 0.47 V owing to a passivation effect. The MIS solar cell with the ZnO NRs exhibited a 35.5% efficiency enhancement compared to that without ZnO NRs. The performance improvement in MIS solar cells with ZnO NRs could be due to multiple reflections of an incident light between the vertically arranged NRs, and then light coupling into the cell. The results show a potential application of ZnO NRs for the performance enhancement of MIS solar cells.