Simultaneous realization of light distribution and trapping in micromorph tandem solar cells using novel double-layered antireflection coatings

Abstract

Implementing antireflection (AR) coatings in micromorph tandem solar cells is a challenging process in which not only more sunlight should get conducted into the cells, but also the current matching between subcells should either be maintained or get improved. In this work, the novel double-layered AR coatings were prepared on either one side or two sides of glass superstrates using hybridized hollow silica nanosphere (HSN) sols. As a result of improvement in light distribution via double-layered AR coatings, the current difference between the top and bottom subcells was decreased to be 0.05mA/cm2, much smaller than that of untreated cells, 0.33mA/cm2. Furthermore, the cells grown on the two-sided AR coated superstrates demonstrated the largest increases in current densities of top and bottom subcells, 4.20% and 7.53%, respectively, which were much higher than those of the cells on one-sided AR coated superstrates. The underlying origin was ascribed to the better light trapping induced by multiscale texturing at front boron-doped zinc oxide (BZO) electrodes, which resulted from the conformal growth of BZO on HSNs with unique surface morphologies. The findings provided a practical way to simultaneously realize light distribution and trapping using the two-sided AR coated glass superstrates without any amendment of layers inside micromorph tandem solar cells.