Comparing photoluminescence imaging and microwave detected photoconductivity for measuring recombination lifetimes of silicon wafers

Abstract

This study investigates the correlation between recombination lifetime and photoluminescence (PL) in silicon solar cells, aiming to evaluate the reliability of Photoluminescence Imaging (PLI) as compared to the well-established Microwave Detected Photoconductivity (MDP) technique. Recombination lifetime is a critical parameter influencing solar cell efficiency, as it determines how long charge carriers persist before recombining. Using both MDP and PLI tools, the recombination lifetimes and corresponding PL grey values of monocrystalline silicon wafers were measured under various thermal and contamination conditions. Heat treatments at 800°C and 950°C, along with deliberate contamination using a copper coin and latex gloves, were employed to produce a wide range of recombination activity across the samples. Data were analysed using ImageJ to correlate PL grey values with MDP-measured lifetimes. A linear relationship of the form Y = 0.0090X, where Y is the recombination lifetime and X is the grey value, was established through regression analysis. Results revealed a consistent relationship between the two measurement techniques, validating the potential of PLI as a rapid and non- destructive proxy for lifetime assessment. The findings support the development of cost-effective and efficient quality control methods in photovoltaic manufacturing by leveraging the complementary strengths of both PLI and MDP.