The reciprocal space can be probed using different experimental methods. In this study, electron diffraction tomography in the TEM is used to characterize the reciprocal space in three-dimensions. Therefore, a conventional single-axis sample tilting setup is used to probe the reciprocal space by sequential sample tilting and electron diffraction pattern acquisition. Advanced data evaluation techniques are used to reconstruct the sampled volume of the 3D reciprocal space. This reconstruction is then used to generate cuts through the reciprocal space differing from the transmission geometry in TEM, creating e.g. cuts in the zx plane, which corresponds to the geometry used in gracing incidence wide angle X-ray scattering (GIWAXS) (Figure 1).

The described method is applied to two different sample systems. The first sample system is an active layer of an organic bulk heterojunction solar cell comprised of the small molecule donor DRCN5T and the acceptor PC71BM (Figure 2). For this sample system energy-filtered selected area electron diffraction is used to exclude inelastic contributions that superimpose the elastic signal. Furthermore, the beam sensitivity of the material system has to be considered carefully during the data acquisition procedure. As second sample system a highly textured AlN layer is used (Figure 2). The pronounced fibre texture and beam insensitivity qualify this material as a highly interesting reference sample system.

The 3D reciprocal space reconstruction based on electron diffraction tomography will be compared to GIWAXS measurements for both sample systems. The latter method utilizes a different experimental setup and radiation source and therefore differs in the way the reciprocal space is probed. As a consequence of the different experimental setups, meaning transmission with electrons in contrast to gracing incidence with X-rays, the resulting cuts of the reciprocal space are perpendicular to each other. The comparison of the two methods entails the already mentioned possibility to generate cuts through the (by electron diffraction tomography) reconstructed 3D volume that correspond then to a GIWAXS-like sampling of the reciprocal space.

Acknowledgement: The authors gratefully acknowledge financial support by the DFG via the Collaborative Research Centre SFB 953 “Synthetic Carbon Allotropes”.