Low-temperature UV ozone-treated high efficiency radial p-n junction solar cells: N-Si NW arrays embedded in a p-Si matrix

High-efficiency radial p-n junction SiNW solar cells have been realized using UV ozone treatment of n-Si NW arrays embedded in a p-Si matrix structure. This structure provides the advantage of homogeneous and continuous front electrode patterning, which results in a lower series resistance than for core-shell morphology. Surface and bulk recombination is chiefly responsible for degrading cell performance with increased SiNW length in spite of enhanced junction area and improved light-trapping capability. In this study we estimated the critical NW length necessary to obtain optimal cell performance with minimum carrier loss in a simple radial p-n junction solar cell. Further low-temperature UV ozone treatments offer the potential to enhance solar cell properties by passivating, by oxidation, the large number of surface defect states.