In-situ study of the interface formation in organic multilayers

Sassella, A.; Borghesi, A.; Campione, Marcello; Raimondo, L; Goletti, C.; Bussetti, Gianlorenzo; Chiaradia, P.

doi:10.1016/j.spmi.2008.02.002

Cited by 1 publication

(1 citation statement)

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“…Growth is a dynamic phenomenon, and transient effects in structural order as well as in the optical properties 20 may occur and have to be investigated in situ and in real-time. [21][22][23][24] Apart from the film structure, also intermolecular coupling can significantly affect the optical properties of the mixed system either due to the differences in the film structure compared with the pure films, which results in changes in the intermolecular interactions between molecules of the same compound, 25 or due to a a) Electronic mail: alexander.gerlach@uni-tuebingen.de possible charge transfer between molecules of the two different compounds. [26][27][28][29][30][31] Pentacene (PEN, C 22 H 14 ) and diindenoperylene (DIP, C 32 H 16 ) are two of the most prominent small-molecule organic semiconductors, 13,[33][34][35][36] which exhibit an anomalous ordering in PEN:DIP blends with a smectic-C-like structure.…”

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confidence: 99%

Structure formation in perfluoropentacene:diindenoperylene blends and its impact on transient effects in the optical properties studied in real-time during growth

Broch

Gerlach

Lorch

et al. 2013

The Journal of Chemical Physics

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We discuss the result of the competing effects of favourable intermolecular interactions and steric incompatibilities due to the size mismatch of perfluoropentacene (PFP) and diindenoperylene (DIP) on the structure formation and associated optical properties in mixed films. Using real-time grazing incidence X-ray diffraction we investigate the size of coherently scattering islands l(s) as a function of film thickness and mixing ratio. We find that for PFP:DIP 1:2 blends l(s) is by a factor of ~4 smaller than in pure DIP films, while l(s) of the PFP:DIP 2:1 blends is not significantly reduced compared with pure PFP. Yet, we observe an increase in l(s) with film thickness for all of the samples, independent on the mixing ratio. In parallel with the structural characterization we investigate the evolution of the absorption spectra in the visible spectral range and its dependence on l(s) in situ during film growth using differential reflectance spectroscopy. We observe a surprisingly strong effect of changes in the structural order on the shape of ε(2, xy)(E), evident by a pronounced evolution of characteristic peaks in the thickness range from 1.6 nm to 9.6 nm. The combined results of the real-time experiments allow to identify the thickness dependent crystal grain size as the origin of the observed transient effects in the absorption spectra.

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