Natalie Stingelin, Georgia Institute of Technology -- In the past decade, significant progress has been made in the fabrication of organic photovoltaic devices (OPVs), predominantly due to important improvements of existing materials and the creation of a wealth of novel compounds. Many challenges, however, still exist. Real understanding of what structural and electronic features determine, for instance, the short-circuit current (Jsc), open-circuit voltage (Voc) and fill factor are still lacking; and the role of charge transfer states and which charge transfer states are critical for efficient charge generation are still debated. Here we discuss relevant structure/processing/performance interrelations using classical polymer processing `tools¿. We present a survey on the principles of structure development of this material family and how it can be manipulated, with focus on how to control the phase morphology and important interfaces (molecular and between different phase regions). Goal is to tailor and tune the final `morphology¿ towards establishing correlations with relevant device characteristics. Examples are given based on polymer:fullerene solar cells as well as solution-processed perovskite structures. For more information, please go to www.materials.princeton.edu