Reciprocity Between Electroluminescence and Quantum Efficiency Used for the Characterization of Silicon Solar Cells

Spectrally and spatially resolved electroluminescence emission of crystalline silicon solar cells is interpreted in terms of two electro-optical reciprocity relations. The first relation links the photovoltaic quantum efficiency to the electroluminescence spectrum. Both methods contain information on recombination and the optical pathlength of the incident light, simultaneously. From the electroluminescence spectrum, we derive the pathlength enhancement factor of textured and untextured crystalline silicon solar cells. Further, we use local quantum efficiency measurements to quantitatively explain light induced current as well as panchromatic electroluminescence images. A second reciprocity relation connects open circuit voltage of a solar cell with the light emitting diode quantum efficiency of the same device. For a given quality of light trapping and a given open circuit voltage, we predict the attainable LED quantum efficiency and verify our results experimentally. Copyright (C) 2009 John Wiley & Sons, Ltd.