The porous silicon emitter concept applied to multicrystalline silicon solar cells

We report on the application of porous silicon (PS) as an antireflection coating material for commercial multicrystalline silicon solar cells. A PS layer was formed on the thin emitter of n(+)/p junctions (0.3 mu m thick) produced for optimal photovoltaic characteristics with the front contact grid already deposited. This technique allows us to restrict PS formation to the areas between the grid fingers without changing the front contact (selective PS formation). Reflectivity measurements, quantum efficiencies and I-V characteristics are presented and carefully compared with the performances of cells using a classical antireflection coating (SiO2 + TiO2) in order to evaluate the effectiveness of PS. The photovoltaic characteristics of the PS n(+)/p junctions are comparable to those of the best multicrystalline solar cells produced commercially by the same manufacturer of the n(+)/p junction. (C) 1997 Elsevier Science S.A.