X-ray radiation damage of organic semiconductor thin films during grazing incidence diffraction experiments

Neuhold, Alfred; Novák, Jiřı́; Flesch, Heinz-Georg; Moser, A.; Djuric, Tatjana; Grodd, Linda; Grigorian, Souren; Pietsch, U.; Resel, Roland

doi:10.1016/j.nimb.2011.07.105

Cited by 24 publications

(25 citation statements)

References 41 publications

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“…Preliminary measurements concerned the control of the exposure time to the highly collimated X-ray synchrotron beam generating photoelectrons which may affect the OFET response on one hand, and consequently the parameters extracted, and, on the other hand cause radiation damage to the organic film. [31][32][33] By applying V DS = V GS = -20 V, the source-drain current (I DS ) and the source-gate current (I GS ) were continuously measured (Figure 2a) while X-ray measurements around the 001 reflection were carried out every 40 minutes (/2 and  scan, RC, reported in Figure S5) to monitor the evolution of stacking layer periodicity. The occurrence of the bias stress during the device operation is evidenced by the characteristic decrease of |I DS |, compensated by the photocurrent generated by Xray irradiation (inset in The RC shift to smaller angles can be ascribed to a lattice expansion along the film thickness (i.e.…”

Section: Resultsmentioning

confidence: 99%

Changes of the Molecular Structure in Organic Thin Film Transistors during Operation

et al. 2015

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Thin films of organic semiconductors have been widely studied at different length scales for improving the electrical response of devices based on them. Hitherto, a lot of knowledge has been gained about how molecular packing, morphology, grain boundaries, and defects affect the charge transport in organic thin film transistors. However, little is known about the impact of an electric field on the organic semiconductor microstructure and the consequent effect on the device performances. To fill this gap, we investigated the evolution of the structure of pentacene thin film transistors during device operation by in situ real time X-ray diffraction measurements and theoretical calculations. We observed for the first time the occurrence of a reversible structural strain taking place during the bias application mainly due to reorientation at the terrace edges of monolayer islands under the effect of electrical field. Strain exhibits the same trend of the threshold voltage hinting to the existence of a direct correlation between the phenomenon of bias stress and the structural modification.2

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Section: Resultsmentioning

confidence: 99%

Changes of the Molecular Structure in Organic Thin Film Transistors during Operation

et al. 2015

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“…The spikes are not reflected in the XRR data, where it has to be stressed that XRR is an integral method. They, however, also could be a consequence of degradation effects of the P3HT layer during the XRR measurements [48].…”

Section: Resultsmentioning

confidence: 99%

X-ray based tools for the investigation of buried interfaces in organic electronic devices

Neuhold

Brandner

Außerlechner

et al. 2013

Organic Electronics

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Graphical abstractHighlights► We fabricated orthogonal soluble polymer stacks and probed the buried interface by X-ray reflectivity. ► Depending on the used solvent of the organic semiconducting material the interface morphology changed significantly. ► Grazing incidence X-ray diffraction exhibits the molecule alignment in the investigated polymer stack. ► The buried interface roughness within the polymer stack was correlated to the OTFT performance containing the stack.

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“…The experiments were performed under a helium atmosphere using the dome of the DHS900 attachment (Resel et al, 2003) to reduce sample degradation (Neuhold et al, 2012). .…”

Section: Methodsmentioning

confidence: 99%

“…On the basis of the known crystal structure of NNN, its electron density is determined to 397 nm À3 which yields a refractive index of n org = 1 À with = 2.48 Â 10 À6 and, finally, C,organic = (2) 1/2 = 0.128 . The critical angle of the amorphous silicon oxide substrate is determined on the basis of electron densities obtained from X-ray reflectivity investigations (Neuhold et al, 2012) to C,substrate = 0.166 for the present X-ray wavelength. The observed peak maximum of the Yoneda peak lies exactly between these two values; however, the experimental setup does not allow separating the two contributions due to limited resolution.…”

Section: Methodsmentioning

confidence: 99%

Multiple scattering in grazing-incidence X-ray diffraction: impact on lattice-constant determination in thin films

Resel

Bainschab

Pichler

et al. 2016

J Synchrotron Radiat

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Dynamical scattering effects are observed in grazing-incidence X-ray diffraction experiments using an organic thin film of 2,2 0 :6 0 ,2 00 -ternaphthalene grown on oxidized silicon as substrate. Here, a splitting of all Bragg peaks in the out-ofplane direction (z-direction) has been observed, the magnitude of which depends both on the incidence angle of the primary beam and the out-of-plane angle of the scattered beam. The incident angle was varied between 0.09 and 0.25 for synchrotron radiation of 10.5 keV. This study reveals comparable intensities of the split peaks with a maximum for incidence angles close to the critical angle of total external reflection of the substrate. This observation is rationalized by two different scattering pathways resulting in diffraction peaks at different positions at the detector. In order to minimize the splitting, the data suggest either using incident angles well below the critical angle of total reflection or angles well above, which sufficiently attenuates the contributions from the second scattering path. This study highlights that the refraction of X-rays in (organic) thin films has to be corrected accordingly to allow for the determination of peak positions with sufficient accuracy. Based thereon, a reliable determination of the lattice constants becomes feasible, which is required for crystallographic structure solutions from thin films.

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X-ray radiation damage of organic semiconductor thin films during grazing incidence diffraction experiments

Cited by 24 publications

References 41 publications

Changes of the Molecular Structure in Organic Thin Film Transistors during Operation

Changes of the Molecular Structure in Organic Thin Film Transistors during Operation

X-ray based tools for the investigation of buried interfaces in organic electronic devices

Multiple scattering in grazing-incidence X-ray diffraction: impact on lattice-constant determination in thin films

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