Understanding the Light‐Intensity Dependence of the Short‐Circuit Current of Organic Solar Cells
Paula Hartnagel, Thomas Kirchartz
Abstract
Abstract In organic solar cells, bimolecular recombination is a key factor limiting the device performance and creating the need for characterization. Light‐intensity‐dependent short‐circuit current density measurements are a frequently used tool to qualitatively analyze bimolecular recombination in a device. When applying a 0D model, bimolecular recombination is expected to reduce the otherwise linear correlation of the short‐circuit current density J sc and the light intensity Φ to a sublinear trend. It is shown by numerical simulations that the slope of the J sc –Φ curve is affected by the recombination mechanism (direct or via traps), the spatial distribution of charge carriers and—in thick solar cells—by space charge effects. Only the combination of these effects allows proper explanation of the different cases, some of which cannot be explained in a simple 0D device model.