Short-circuit Current Density Imaging Methods for Silicon Solar Cells

Recently, several novel methods have been proposed to image short-circuit current density jsc based on diverse physical principles. This work compares these methods and points out physical limitations, advantages and drawbacks of each approach. One method based on photoluminescence (PL) imaging and two methods based on dark and illuminated lock-in thermography (DLIT / ILIT) are discussed. As a versatile reference technique for jsc mapping, spectrally-resolved light-beam induced current (SR-LBIC) is applied. Experimental results for crystalline silicon solar cells with varying substrate properties, rear-side passivation schemes and process-induced defects are presented. Investigated parameters are quantitative accuracy of local jsc, spatial resolution, measurement time, spectral excitation dependency and calibration. Furthermore, robustness towards locally increased series resistance Rs and injection-dependent recombination is discussed along with proneness to artefacts due to local shunts, spatially varying optics and photogeneration, and fitting algorithm artefacts.