One shot mapping of minority carrier diffusion length in polycrystalline silicon solar cells using electroluminescence

The novel technique of analyzing the spatial distribution of minority carrier diffusion length was investigated in detail by utilizing the photographic surveying of electroluminescence emitted from polycrystalline Si cells. The emitted infrared light (peak wavelength: 1150 nm) from a sample cell under the forward bias was captured by a cooled CCD camera. The intensity was found to be proportional to the minority carrier diffusion length regardless of the running current density, which gave the quantitative information of the minority carrier diffusion length distribution with high reliability. The deteriorated areas and/or aggregation of defects were detected by a simple one-shot capturing of the emitted light.