Berlin 2012 – scientific programme

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DS: Fachverband Dünne Schichten

DS 44: Poster IV: Thin film photovoltaics; Organic electronics and photovoltaics (jointly with CPP, HL, O); Organic thin films; Trends in atomic layer deposition (Focused session)

DS 44.50: Poster

Friday, March 30, 2012, 09:30–12:00, Poster E

Organophosphonate monolayer functionalization of planar and nano-porous aluminum oxide — •Anshuma Pathak¹, Björn Braunschweig², Achyut Bora¹, Hongdan Yan³, Peter Lemmens³, Winfried Daum⁴, and Marc Tornow¹ — ¹IHT, TU Braunschweig, Germany — ²LFG, University of Erlangen-Nuremberg, Germany — ³IPKM, TU Braunschweig, Germany — ⁴IEPT, TU Clausthal, Germany

Self-assembled monolayers (SAMs) of molecules on metal oxides are of increasing interest for organic electronics. We have deposited SAMs of aliphatic organophosphonates on different aluminum oxide substrates, including sapphire, polycrystalline Al/Al₂O₃ and nano-porous, amorphous aluminum oxide (AAO). Water contact angles in the range 95-120^∘ and AFM measurements with RMS roughness down to ∼0.2 nm revealed homogeneous SAM formation. We used FTIR and Sum Frequency Generation (SFG) spectroscopy to investigate the molecular ordering of the layers. The positions of the asymmetric and symmetric CH₂ vibrational peaks determined by FTIR were below 2918 cm⁻¹ and below 2850 cm⁻¹, respectively, indicating densely packed, crystalline layers. Remarkably, we observed only very small or even no intensity of CH2 peaks in the SFG spectra on sapphire and AAO. We conclude that the molecules in these SAMs are highly organized, practically in an all-trans conformation.

Work supported by the NTH School for Contacts in Nanosystems and by the Braunschweig International Graduate School of Metrology (IGSM).