Short-circuit current density imaging methods for silicon solar cells

Recently, several novel methods have been proposed to image short-circuit current density j(sc) 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 j(sc) 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 j(sc), spatial resolution, measurement time, spectral excitation dependency and calibration. Furthermore, robustness towards locally increased series resistance R-s, and injection-dependent recombination is discussed along with proneness to artefacts due to local shunts, spatially varying optics and photogeneration, and fitting algorithm artefacts. (C) 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).