Quantitative Shunt Determination in Organic Solar Modules Using Lock-in-Thermography

Abstract

Shunts in organic solar modules are known to be detrimental with respect to their low light behavior. In all known methods to measure the ohmic shunt value the cell has to be directly accessible. To determine shunt values in solar modules consisting of series connected bulk-heterojunction organic solar cells, in this manuscript a precise method is presented where the single cells cannot be accessed separately. It will be shown that the shunts that are detected using Illuminated Lock-in-thermography are strongly ohmic, although parallel resistances in organic solar cells usually show a strong dependence on the illumination intensity. Therefore the defects can be assigned a distinct ohmic value.