Regensburg 2010 – scientific programme
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KR: Fachverband Kristallographie
KR 6: Topical Session Photovoltaic Materials II (with MM and BV MatWerk)
KR 6.5: Talk
Wednesday, March 24, 2010, 12:45–13:00, H4
Effect of film thickness, type of buffer layer, and substrate temperature on the morphology of dicyanovinyl-substituted sexithiophene films — •Alexandr A. Levin1, Marieta Levichkova1, Martin Pfeiffer2, Dirk Hildebrandt2, David Wynands1, Chris Elschner1, Karl Leo1, and Moritz Riede1 — 1Institut für Angewandte Photophysik, Technische Universität Dresden, 01062 Dresden, Germany — 2Heliatek GmbH, 01187 Dresden, Germany
Dicyanovinyl-substituted sexithiophenes (DCV6T) are promising photoactive materials [1]. The influence of the film thickness, type of buffer underlayer, and deposition substrate temperature on the morphology of the DCV6T layers is investigated by means of X-ray diffraction and X-ray reflectivity methods. A neat Si wafer or a Si wafer covered by a 15 nm buffer underlayer of fullerene C60 or 9,9-Bis[4-(N,N-bis-biphenyl-4-yl-amino)phenyl]-9H-fluorene (BPAPF) is used as substrate.
The crystalline nature and ordered molecular arrangement of the films are proven down to 6 nm film thickness. With increasing substrate temperature or film thickness, the DCV6T film relaxes, resulting in reducing the interplane distances (from 11.29(5) Å to 10.78(5) Å) closer to the bulk value (10.14(1) Å). Considering the same thickness, the DCV6T film relaxes for growth on Si to BPAPF to C60. Thicker films are characterized by smaller density and higher roughness. A thin (some nm-thick) intermediate layer with linear density-gradient is formed in DCV6T/C60 interface for the films with buffer C60 layer.
[1] D. Wynands et al., J. Appl. Phys. 106 (2009) 054509.