Mixed Self-Assembled Layers of Phosphonic Acids

Prado, Mariana C.; Neves, Bernardo R. A.

doi:10.1021/la902240d

Cited by 12 publications

(15 citation statements)

References 39 publications

(76 reference statements)

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“…18 To fine-tune these changes in properties, it is possible to utilize mixed SAMs. 19 These are used for the fabrication of memory OTFTs, 20 with integrated charge storage SAMs consisting of fullerene functionalized PA and insulating alkyl-PA molecules, and active charge-transport layers in self-assembled monolayer field-effect transistors (SAMFETs). 21,22 Another method to modify SAMs and to obtain specific properties is the use of exchange reactions.…”

Section: Self-assembly Of Phosphonic Acid Based Moleculesmentioning

confidence: 99%

Structural Investigations of Self-Assembled Monolayers for Organic Electronics: Results from X-ray Reflectivity

et al. 2015

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Self-assembled monolayers (SAMs) have been established as crucial interlayers and electronically active layers in organic electronic devices, such as organic light emitting diodes (OLEDs), organic photovoltaics (OPVs), organic thin film transistors (OTFTs), and nonvolatile memories (NVMs). The use of self-assembling functionalized organic molecules is beneficial due to mainly three advantages compared with common thin film deposition approaches. (1) Molecular self-assembly occurs with surface selectivity, determined by the interaction between the functional anchor group of the organic molecules and the target surface. (2) The film thickness of the resulting layers is perfectly controllable on the angstrom scale, due to the self-terminating film formation to only a single molecular layer. And finally, (3) the wide variability in the chemical structure of such molecules enables different SAM functionalities for devices, ranging from electrical insulation to charge storage to charge transport. The SAM approach can be further expanded by employing several functionalized molecules to create mixed SAMs with consequently mixed properties. The function of SAMs in devices depends not only on the chemical structure of the molecules but also on their final arrangement and orientation on the surface. A reliable and nondestructive in-depth characterization of SAMs on nonconductive oxide surfaces is still challenging because of the very small thickness and the impracticality of methods such as scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). In this Account, we illustrate how X-ray reflectivity (XRR) provides analytical access to major questions of SAM composition, morphology, and even formation by means of investigations of pure and mixed SAMs based on phosphonic acids (PAs) of various chain structures on flat alumina (AlOx) surfaces. XRR is an analytical method that provides access to spatially averaged structural depth profiles over a relatively large area of several square micrometers. The key outcome of XRR, the surface-normal electron density profile of the SAMs, leads to precise information on the SAM thickness with subangstrom resolution and allows for the determination of molecular tilt angles and packing densities. We have systematically increased the chemical complexity of PA molecules and the resulting SAMs, utilizing XRR to provide insight into the SAM structures. In SAMs composed of functionalized molecules or complex chain structures, the distribution of electron rich and electron poor signatures is detected and thus the molecular order within the SAM is determined. In mixed SAMs of two different molecular species, electron density profiles reveal the morphology and how the surface-normal structure changes if one component of the mixed SAM is altered. Furthermore, XRR was applied to investigate in situ the self-assembly of functionalized PA molecules from solution by tracking the monolayer growth over time. Even though the results provided by XRR on in-plane molecular arrangement a...

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Section: Self-assembly Of Phosphonic Acid Based Moleculesmentioning

confidence: 99%

Structural Investigations of Self-Assembled Monolayers for Organic Electronics: Results from X-ray Reflectivity

et al. 2015

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“…In a second publication, quantities of octadecyl and octylphosphonic acid varied and the inuence of water on the layer morphology was studied. 145 Taking into account these parameters, a lot of different structures (monolayers, bilayers, rods, and branches) were created showing the versatility of the system. In the third study, long range order was monitored by wide-angle scattering in respect to temperature and a phase diagram was extracted.…”

Section: Calcium Carbonatementioning

confidence: 99%

Organophosphonates as anchoring agents onto metal oxide-based materials: synthesis and applications

et al. 2014

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“…The approach of generating mixed substituted surfaces was also investigated in the presented work to study its effect on the formation of dispersions in organic media, for example to improve the deagglomeration behavior of nanoparticles in dispersions. Prado et al have studied the coadsorption approach on macroscopic flat surfaces for organophosphorus mixed monolayer [19] but this concept has not been applied to transition metal oxide colloids before.…”

Section: Introductionmentioning

confidence: 99%

Tuning the self-assembled monolayer formation on nanoparticle surfaces with different curvatures: Investigations on spherical silica particles and plane-crystal-shaped zirconia particles

Feichtenschlager

Lomoschitz

Kickelbick

2011

Journal of Colloid and Interface Science

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Graphical abstractAmorphous spherical silica and plane-crystal-shaped zirconia particles were prepared and functionalized with long alkyl chain coupling agents. The effect of the nanoscopic curvature and the co-functionalization with a second coupling agent was investigated.Highlights► Alkyl-chain ordering on curved and plane nanoscopic surfaces. ► Disturbing self-assembled monolayer formation on nanoparticles by co-functionalization. ► Improvement of the dispersion behavior of nanoparticles by co-functionalization of their surface.

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Mixed Self-Assembled Layers of Phosphonic Acids

Cited by 12 publications

References 39 publications

Structural Investigations of Self-Assembled Monolayers for Organic Electronics: Results from X-ray Reflectivity

Structural Investigations of Self-Assembled Monolayers for Organic Electronics: Results from X-ray Reflectivity

Organophosphonates as anchoring agents onto metal oxide-based materials: synthesis and applications

Tuning the self-assembled monolayer formation on nanoparticle surfaces with different curvatures: Investigations on spherical silica particles and plane-crystal-shaped zirconia particles

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