Effect of laser-induced conversion of silicon nitride to silicon oxy-nitride on antireflective properties of passivation layer in polysilicon solar cells

Abstract

Silicon solar cell technology is dominating in the photovoltaic industry, however, a further increase in cost-effectiveness is needed. This can be achieved by increasing the light coupling in the active layer of the cell. Passivation layer of the commercial polycrystalline silicon solar cells was textured using the laser beam interference patterning technique to obtain enhanced optical properties due to the formation of periodic refractive index grating. As a consequence of laser irradiation, passivation layer of silicon nitride was partially oxidized at the intensity peaks of the interference distribution. Periodic distribution of oxidized areas was found by EDS. Investigation of optical and electrical properties of the laser treated solar cells shows increased light coupling and better photo-electrical performance. Simulations were carried out to evaluate the influence of refractive index grating formed in silicon oxy-nitride to optical properties of the patterned solar cells. Periodic oxide grating was found to be more efficient for light coupling in thinner film structures. The results of this work may find applications in other fields as it allows alteration of material composition in the well-defined periodic pattern.