Berlin 2015 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 10: Organic Electronics and Photovoltaics (organized by DS)
TT 10.9: Vortrag
Montag, 16. März 2015, 11:30–11:45, H 2032
Charge separation and C60 crystallinity in bulk heterojunction solar cells: the decisive role of device architecture — •Felix Schell1,2, Michael Scherer1,3, Diana Nanova1,2,3, Anne Katrin Kast2,4, Wolfgang Kowalsky1,2,3, Rasmus R. Schröder1,4,5, and Robert Lovrincic1,3 — 1InnovationLab GmbH, Heidelberg — 2Kirchhoff-Institute for Physics, Heidelberg University — 3Institute for High-Frequency Technology, TU Braunschweig — 4CellNetworks, BioQuant, Heidelberg University — 5Center for Advanced Materials, Heidelberg University
The crucial influence of C60 crystallinity on the charge separation in organic solar cells (OSC) has been realized very recently. Here, we show the importance of the device architecture on C60 crystallisation in the bulk-heterojunction (BHJ). Active layer morphology of small molecule BHJ OSC and its influence on device performance are studied by means of energy-filtered transmission electron microscopy (EFTEM) and electrical characterization. The influence of substrate temperature during deposition and of pure sublayers is assessed. BHJs fabricated at room temperature are found to be finely mixed and amorphous, whereas the corresponding films deposited onto heated substrates show pronounced phase separation. Despite these clear morphological changes, substrate heating does not increase efficiency of OSCs in a non-inverted device architecture. Improvements found in literature for inverted cells can be attributed to stronger acceptor crystallization, present, if deposited onto a pure C60 layer but not with an F4ZnPc substrate, leading to more efficient exciton dissociation.