Analysis of electroluminescence from silicon heterojunction solar cells

The density of defects at the interface between the amorphous and crystalline silicon layers limits the photovoltaic device performance of amorphous silicon / crystalline silicon heterojunction solar cells. We investigate the electroluminescence properties of these devices for a variation of interface defect densities. Electroluminescence efficiency, dark saturation current density and open-circuit voltage are related via Planck’s generalized law and the current-voltage relations. These analytical relations are reproduced by the full numerical simulation of the solar cell behavior, especially the exponential dependence of the electroluminescence efficiency on the open-circuit voltage. Experimentally we show that a planar silicon heterojunction solar cell with high open-circuit voltage achieves an electroluminescence efficiency around 0.13%.