Stratingh seminar - Dirk Vanderzande: Organic Photovoltaics:Understanding and Controlling the nano-morphology of the active layer

The field of Organic PhotoVoltaics (OPV) has witnessed a fierce development since the first solar cells of this kind were built in the 90's. Since then the efficiency has increased to almost 12% in a single junction. This progress is a result of a combination of new materials, insight in working principles and new architectures. Material classes will be discussed, also with examples of work at imo-imomec. Secondly efficiency is critical dependent on achieving an intimately mixed nano-morphology of the do-nor (conjugated polymer) and acceptor (fullerene) material. This creates a bulk heterojunction which allows for obtaining high performance. The physical-chemistry behind these material systems starts to be unraveled and is essential in understanding what is going on. Recently a study was started in which different interlayers were used which lead to improvements of more than 15% of the initial achieved effi-ciency. The last critical parameter is lifetime and understanding aging of devices. Some examples of this work will also be presented, specifically related to the study of the behavior of the nano-morphology un-der thermal stress. Finally the issue of scalability of the synthesis of materials used in OPV will be discussed.