Dresden 2014 – scientific programme
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DS: Fachverband Dünne Schichten
DS 27: Organic Thin Films II
DS 27.2: Talk
Wednesday, April 2, 2014, 15:15–15:30, CHE 91
The role of a molecular dipole in thin-film growth kinetics: In situ X-ray studies of 6P and 6P-3,5-F2 — •Anton Zykov1, Sebastian Bommel1,2, Peter Schäfer1, Francesco Carlà3, Roberto Felici3, and Stefan Kowarik1 — 1Inst. f. Physik,Humboldt Universität Berlin — 2DESY, Deutsches Elektronen-Synchrotron, Hamburg — 3ESRF, Grenoble
An understanding and ideally a control of thin-film growth is needed to rationally fabricate organic-inorganic heterostructures for optimized devices like efficient OLEDs. However, growth control is up to now almost exclusively limited to substrate temperature and growth rate. The incorporation of tunable static dipoles into well-known organic molecules may thus establish a new degree of freedom to design the thin-film morphology. Here we want to present first results of a growth study of 6P and its dipolar derivative 6P-3,5-F2 on SiO2. The films were deposited in a vacuum chamber by OMDB under variation of the growth rate and the substrate temperature. Simultaneous in situ X-ray measurements of the growth oscillations and GISAXS were carried out at the ID03 beamline at the ESRF to access growth-mode, island-sizes and -densities, which in the end determine the film morphology. We find that films from the dipolar molecule 6P-3,5-F2 form smaller islands while at the same time yielding smoother films than 6P. Interestingly the inter-layer crystallographic orientation is also lost in 6P-3,5-F2. These results suggest a different growth mode due to the additional source of disorder through random orientation of dipoles.