Internal morphology of BHJ organic solar cells by GISAXS

Organic solar cells have attracted much interest in the field of organic electronics in recent years. The construction of bulkheterojunction solar cells from two organic materials fulfills the three important criteria for high efficiency of organic solar cells. A large interfacial area, the characteristic internal length should be in the same range as the diffusion length of the excitons in the specific material and highly efficient transport of the charge carriers to the electrodes. The large variety of materials allows a proper choice of the materials. The materials that have been chosen for the present project fulfill these criteria since organic solar cells have already been realized based on them. Nevertheless the internal structure and how it can be influenced during the device fabrication is still not clear. The combination of GISAXS to investigate the internal morphology with the electrical device characterization provides an insight in the structure to charge carrier generation and transport relationship. Intentional variation of the internal structure yields information on a more abstract level that yields to a profound understanding of how charge carrier generation and transport in organic compounds can be understood. For the understanding of the internal morphologies not only blend structures have to be investigated. The crystallization behavior and the influence of temperature have to be explored. The mixing behavior will be investigated and how it can be influenced since this mixing is seen as driving force for the creation of different types of internal morphology. This gives insights into the stability of the system in a certain blend ratio and temperature region.