Detection of oxygen precipitate dark rings in solar cell luminescence using gray level co-occurrence matrix

Abstract

The presence of dark swirls or rings in luminescence image of a solar cell is usually caused by oxygen precipitate during fabrication of a solar cell. This is not desirable as it could cause a drop in efficiency of the cell. An application of gray level co-occurrence matrix (GLCM) is presented to detect such dark swirls or rings in both photoluminescence (PL) and electroluminescence (EL) images. It was found that the energy values calculated from a GLCM has a good separation between defective and non-defective images. A threshold was established based on the energy values and was then used to perform classification. Experiments have shown that this method provides a good result with minimal under-rejection and over-rejection rate for both PL and EL.