Regensburg 2013 – scientific programme

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O: Fachverband Oberflächenphysik

O 61: Organic Electronics and Photovoltaics I (jointly with CPP, DS, and HL)

O 61.2: Talk

Thursday, March 14, 2013, 10:00–10:15, H34

Influence of fluorine content in manipulating the nanomorphology of PTB7:PC70BM bulk heterojunction systems — •Shuai Guo¹, Jing Ning¹, Volker Körstgens¹, Yuan Yao¹, Chen Lin¹, Stephan Roth², and Peter Müller-Buschbaum¹ — ¹TU München, Physik Department, LS Funktionelle Materialien, James-Franck-Str. 1, 85748 Garching, Germany — ²HASYLAB at DESY, 22603 Hamburg, Germany

Polymer-based photovoltaics have drawn tremendous attention in both basic research and application fields during the last decade. Here, the up-to-date highest efficient bulk heterojunction system PTB7 with varied fluorine content and the fullerene derivative PC70BM are thoroughly investigated. It is known that the amount of fluorine along the polymer chain strongly influences the film formation and therefore the solar cell performance. Additionally, it is of great interest to explore the effect of solvent additive 1,8-diiodooctane (DIO) on differently fluorinated films. To address the relation between the morphology and efficiency completely, a series of measurements have been done. The film surface structure is investigated by optical microscopy and AFM. The inner film structures, crystal orientation as well as the crystallinity are probed by advanced scattering techniques such as XRR, GISAXS and GIWAXS. By integrating all data, the three-dimensional morphology of the active layer is detected. Consequently, the different morphologies introduced by varying the fluorine content and the addition of DIO are determined and compared with the corresponding performance of these systems.