Incorporation of spatially-resolved current density measurements with photoluminescence for advanced parameter imaging of solar cells

The spatial distribution of device performance parameters of solar cells provides important insight into their operation, including the type and magnitude of conversion losses and potential areas of improvement. In most of the procedures used to create these parameter images, a uniform (i.e., global) short-circuit current density (JSC) is usually assumed. However, JSC is known to vary over the surface of a solar cell, especially in polycrystalline absorber materials like multicrystalline silicon. In this work, a high speed quantum efficiency measurement rastered over the surface of a solar cell is used to obtain images of JSC. These JSC images are then used to calculate images of series resistance, dark saturation current density, fill factor, and conversion efficiency. Comparisons are made between the images created with a global JSC and with the spatially-resolved JSC. Negligible variation is observed in the series resistance and dark saturation current density images, but a drastic change is observed in the efficiency images between these two methods.