Limitations of photoluminescence based external quantum efficiency measurements

The spectral response of photoluminescence is a contactless method that provides a measurement of the relative external quantum efficiency of silicon solar cells and wafers. This paper elaborates on a few limitations of this measurement technique to measure the actual external quantum efficiency. Firstly, this method is accurate only if the measured luminescence originates from the radiative recombination of voltage dependent carriers. This paper investigates the impact of luminescence from other spurious sources of luminescence, such as from dielectric layers, on the measurement. Secondly, the paper investigates the impact of angle of incidence of the excitation source on the measurement. This is relevant for LED based light sources, which typically have a high emission angle.