2D mapping of the electron beam induced current (EBIC) in organic solar cells

Electron beam induced current (EBIC) measurements were used to produce 2D nanoscale maps for investigating the homogeneity of solar cells. These maps are acquired by putting the electron beam of a scanning electron microscope (SEM) in spot mode and using a programmable sample stage to move the solar cell under the stationary beam. The electron beam generates electron-hole pairs in the solar cell much like light does in normal operation. The variations in the EBIC signal can be attributed to changes in the morphology. By comparing these measurements with morphological information of the devices, one can identify the cause of inferior performance which should then lead to an improvement of further devices. It should be mentioned that long time exposures to an electron beam destroys the organic semiconductors. Studies were performed to determine the acceptable electron dose during the measurement.