Conversion Efficiency Enhancement of Multi-crystalline Si Solar Cells by Using a Micro-structured Junction

A new approach for enhancing the conversion efficiency of solar cells is proposed. A surface with columnar structures is employed on the fabrication of multi-crystalline silicon solar cells, for increasing the collection probability of photon-generated minority carriers in the cells. For comparison, three types of surfaces (planar surface, surfaces with columns of 12 μm in radius and columns of 9 μm in radius, respectively) are used. It is demonstrated that the cells with columnar structured surfaces have better spectral response and higher efficiencies than the cells with planar surface, while the cells with columns of 9 μm in radius show better spectral response than the cells with columns of 12 μm in radius. However, the cells with columns of 12 μm exhibit higher efficiencies than the cells with columns of 9 μm in radius for their difference in fill factors. Moreover, the effect of the columnar structured surface on the minority carrier collection efficiency is verified with wafers of different minority carrier lifetimes (0.5 μs and 1.0 μs). This work may significantly consider its potential in the manufacturing of high-efficiency solar cells at low cost by using low quality materials.