Impact of defect type on hydrogen passivation effectiveness in multicrystalline silicon solar cells

In this work we examine the effectiveness of hydrogen passivation at grain boundaries as a function of defect type and microstructure in multicrystalline silicon. We analyze a specially prepared solar cell with alternating mm-wide bare and SiN_x-coated stripes using laser beam-induced current (LBIC), electron backscatter diffraction (EBSD), synchrotron-based X-ray fluorescence microscopy (μ-XRF), and defect etching to correlate pre- and post-hydrogenation recombination activity with grain boundary character, density of iron-silicide nanoprecipitates, and dislocations. This study reveals that the microstructure of boundaries that passivate well and those that do not differ mostly in the character of the dislocations along the grain boundary, while iron silicide precipitates along the grain boundaries (above detection limits) were found to play a less significant role.