Quantitative measurement and modeling of spontaneous emission efficiency of forward biased multi-junction solar cells

The spontaneous emission efficiency (η_rad) of the subcells in a multi-junction solar cell under forward bias yields information about the subcell material quality. Electroluminesence measurement, calibrated with a technique that takes advantage of the luminescence coupling between subcells, is used to determine η_rad as a function of injection current. The InGaAs subcell's η_rad is also fitted to a device model using the PC1D drift-diffusion simulation software to extract the SRH lifetime of the p-n junction base region.