Analytical expressions for spectral composition of band luminescence from silicon solar cells under optical and electrical bias

Abstract

Luminescence imaging, utilizing optical and/or electrical excitation, is now a widely used characterization technique for silicon devices, particularly solar cells. Analytical solutions for the spectral distribution of band luminescence from planar silicon solar cells, including the previously neglected junction depletion region, are reported showing the dependence on wavelengths of optical excitation and emission, exciting voltage and the relevant device material and optical parameters. It is shown that solutions for all combinations of optical and electrical excitation modes under low-level injection can be expressed as superposition of photoluminescence at short circuit and electroluminescence in the dark. Important reciprocal relations between luminescence and its reverse absorption-related process are also discussed as is application of the solutions to textured devices.