Electroluminescence imaging and light-beam induced current as characterization techniques of multi-crystalline si solar cells

Abstract

There is an increasing demand for characterizing multicrystalline solar cells at different stages of its service life. Luminescence techniques, e.g. electroluminescence (EL) and photoluminescence (PL), have acquired a paramount interest in the last years. These techniques are used in imaging mode, allowing to take a luminescence picture at a full wafer/cell scale. This imaging approach is fast and sensitive, but has a low spatial resolution, which avoids a detailed analysis of the defect distribution, which can led to misinterpretations about critical parameters as the minority carrier diffusion length, or the internal and external quantum efficiencies. If one complements these techniques with high spatial resolution techniques, such as light beam induced current (LBIC), one can study the electrical activity of the defects at a micrometric scale, providing additional understanding about the role played by the defects in full wafer/cell luminescence images. The combination of the macroscopic and microscopic resolution scales is necessary for the analysis of the full luminescence images in mc-Si solar cells.