Optimization of porous silicon multilayer as antireflection coatings for solar cells

We present results of numerical simulation of optimized porous silicon (PS) multilayers used as antireflection coatings. For the simulations we introduce a figure of merit, which has into account the transmittance of PS multilayers, the solar cell internal spectral response and the solar spectrum. Using a realistic range of porosities in the simulations (from 40% to 90%) we found an optimal three layers configuration, which transfers to the cell 95.7% of the whole usable power. This value represents the 99.8% of the maximum attainable using the complete porosity range (from 0% to 100%). We fabricate the optimal PS three layers, achieving power transference to the substrate of 95.2%. In addition, taking advantage of the PS fabrication characteristics, we transferred a PS multilayer with specific optical response onto a crystalline silicon solar cell. This allows obtaining a tunable spectral response of the solar cell demonstrating the feasibility of transfer the porous antireflection coating onto any optical device.