Dresden 2014 – scientific programme

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O: Fachverband Oberflächenphysik

O 43: Organic Electronics and Photovoltaics IV (CPP jointly with DS, HL, O)

O 43.4: Talk

Wednesday, April 2, 2014, 10:15–10:30, ZEU 260

The role of processing additives in Organic Solar Cells after the preparation process — •Stefan Väth¹, Andreas Baumann¹, Andreas Sperlich¹, Carsten Deibel¹, Milutin Ivanovic², Heiko Peisert², Thomas Chassé², and Vladimir Dyakonov^1,3 — ¹Experimental Physics VI, Julius Maximilian University of Würzburg, 97074 Würzburg — ²Eberhard Karls University Tübingen, 72076 Tübingen — ³ZAE Bayern, 97074 Würzburg

Processing additives are widely used in the preparation of new high performance bulk heterojunction organic solar cells to improve the power conversion efficiency (PCE) significantly. They act as selective solvent for fullerenes and are therefore improving the morphology of the active area. Nevertheless the question wether or not these co-solvents remain in the organic solar cells after the preparation process occurs. This question could be solved by investigating blends consisting of the material system PTB7:PC₆₀BM processed with the additives diiodooctane (DIO), octanedithiol (ODT) and without additives as reference. We used the spin sensitive measurement technique light induced Electron Paramagnetic Resonance (LESR) to distinguish between positive polarons on the polymer and negative charges on the fullerene by their different g-factors. Together with Photoelectron Spectroscopy (PES) measurements we could show that the additive DIO remains partly inside the active layer of organic solar cells even after a high vacuum preparation step. We propose that they do not only lead to an improved morphology, but also to a doping effect.