We demonstrate the fabrication and characterization of LED device based on self-assembled films of (PVPy/SPS) where PVPy stands for Poly(4-vinyl pyridine) with additional transport layers such as poly-vinyl-carbazole (PVK) and 2-(4-biphenylyl)-5-(4-tertbutyphenyl) -1,3,4-oxidiazole (PBD). The self-assembly is based on the electrostatic interaction; the charge on PVPy is generated by the protonation process. The EL properties of the device ITO/PVK/(PVPy/SPS)/Al and ITO/(PVPy/SPS)/PBD/Al are measured and discussed.

A new approach, molecular layer epitaxy (MLE), is introduced for the vapor-phase assembly of organic multilayers integrated in molecular electronic devices. The MLE approach uses carrier gas assisted epitaxial deposition, covalent bonding, and horizontal π stacking in a pulsed mode for layer-by-layer growth of 1,8:4,5-naphthalenetetracarbodiimide with a hexamethylene spacer 

Derivatives of quinolinium iodide have been found to exhibit second-order nonlinear optical (NLO) response in their crystalline form. The quaternary amine functionality is introduced as an electron-withdrawing group in NLO-active chromophores. While their electron-accepting capabilities are somewhat weaker than those of the nitro group, these organic salts show a much more favorable transparency−nonlinearity tradeoff for blue second harmonic generation (SHG) NLO applications. Here we present crystal growth and characterization via X-ray diffraction (XRD), NMR, FTIR, and optical spectroscopy measurements. Experimental linear optical features are fully consistent with INDO/SCI−SOS theoretical calculations. These latter provide a rationale for the NLO response of these materials. Calculations predict a sizable molecular nonlinearity, which parallels the wavelength of the lowest charge-transfer transition. In addition, a direct correlation between SHG powder response to the β crystallographic angle is observed.

In this paper we introduce the Molecular Layer Epitaxy (MLE) method for epitaxial growth of covalently-linked organic multilayered structures. This method combines vapor phase and solution based multilayers assembly techniques in a unified concept. The MLE approach was proved fruitful by applying Chemical Vapor Deposition (CVD) techniques. The resulting MLE-derived low-dimensional multilayered structures exhibited high structural regularity and thermal stability. The above vapor phase assembly technique led to the formation of organic multiple quantum wells (OMQW) structures, where the solid-state electronic properties are governed by finite size effects. The various emitting species in the solid state were studied by modeling intermolecular interactions in solution. The strong tendency for π-aggregation in model compounds is evident in their crystal structure as well. This driving force for in-plane stacking also enhances the mobilities of electrons with-in this layer leading to unique electroluminescent properties. The suggested MLE approach for multilayered thin film deposition should enable the future advance in areas of material science connected with nano-technologies, and better understanding of fundamental issues in quantum mechanic and solid state physics.