Characterisation of rough reflecting substrates incorporated into thin-film silicon solar cells

Four different categories of rough reflecting substrates as well as a single periodic grating are incorporated and tested within n-i-p type amorphous silicon (a-Si:H) solar cells. Each category is characterised by its own texture shape; dimensions were varied within the categories. Compared to flat reflecting substrates, gains in short-circuit current density (J(sc)) up to 20% have been obtained on rough reflecting plastic substrates. As long as (1) the characteristic dimensions of the textures are lower than the involved light wavelengths, (2) the textures do not present any defects i.e. as long as they do not have large craters or bumps spread over the surface, the root mean square roughness (delta(RMS)) as well as the ratio of average feature height to average period can be used to evaluate the gain in J(sc); if each category of randomly textured substrates is considered separately, the haze factor can be used to estimate delta(RMS) and thereby the gains in J(sc). Copyright (C) 2006 John Wiley & Sons, Ltd.