High current, thin silicon-on-ceramic solar cell

Abstract

Thin-film polycrystalline silicon solar cells offer the potential to achieve 19% efficient photovoltaic power conversion. Well-designed, 20-100 micron thick, thin-film silicon solar cells can achieve high efficiency by employing light trapping and back surface passivation. Low cost is achieved by minimizing the amount of feedstock silicon required per watt of power output. Electrically insulating supporting substrates enable monolithic, series-connected submodules. A solar cell device comprised of a 20 micron thick layer of silicon grown on an insulating ceramic substrate, designed to effect light-trapping and back surface passivation, has resulted in an independently verified short circuit current of 25.8 mA/cm2. Analysis of the spectral response of the solar cell indicates the presence of both light-trapping and back surface passivation with an effective diffusion length in excess of twice the device thickness.