pH-dependent conductance behaviors of layer-by-layer self-assembled carboxylated carbon nanotube multilayer thin-film sensors

Author(s):  
Dongjin Lee ◽  
Tianhong Cui
2010 ◽  
Vol 11 ◽  
pp. 1-6 ◽  
Author(s):  
Sujira Promnimit ◽  
Joydeep Dutta

In this work, we report the directed self organization of multilayer thin film devices with colloidal nanoparticles through Layer-by-Layer (LbL) technique [1]. Self-organization of nanoparticles into assemblies to create novel nanostructures is getting increasing research attention in microelectronics, medical, energy and environmental applications. Directed self-organization of nanoparticles [2] into multilayer thin films were achieved by LbL growth through the interaction of oppositely charged of colloidal nanoparticles on substrates of any kind and shapes. Multilayer thin film devices were fabricated using multilayers of gold (conducting) nanoparticles separated by a dielectric nanoparticulate layer of zinc sulphide. The thin films obtained have been studied extensively and the changes in surface morphology, the optical absorption characteristics, thickness, uniformity, adhesion, and conduction behavior are reported. Current voltage (I-V) characteristics of multilayer devices with an increasing number of deposition cycles show an initial current blockade until an onset voltage value, which increases linearly upon the additional layers stacked in devices [3]. A conductive behavior of the device was observed upon exceeding the onset voltage. Moreover, I-V behavior showed that the conduction onset voltage increases linearly depending on the numbers of layers in the final device controlled by the deposition cycles. Systematic I-V characteristics in the forward and reverse biased conditions demonstrated rectifying behaviors in the onset of conduction voltage which makes these films attractive for future electronic device applications.


2008 ◽  
Author(s):  
Akos Kukovecz ◽  
Péter Heszler ◽  
Krisztián Kordás ◽  
Siegmar Roth ◽  
Zoltán Kónya ◽  
...  

2000 ◽  
Vol 660 ◽  
Author(s):  
Soo-Hyoung Lee ◽  
J. Kumar ◽  
S. K. Tripathy

ABSTRACTIn this work, the fabrication and performance of thin film optical chemical sensors based on the fluorescence quenching of indicator molecules by several analytes such as organic nitro compounds or metal ions are described. To fabricate the sensors, a fluorescent molecule, 1- hydroxypyrene-3,6,8-trisulfonate or pyrene methanol, was covalently incorporated into poly(acrylic acid) (PAA) and subsequently the polymers were assembled with a polycation employing electrostatic layer-by-layer self-assembly into thin film structures. Fluorescence intensities decreased with increasing concentration of analytes. Quenching behavior follows Stern-Volmer bimolecular quenching kinetics. Linear increase in absorbance, film thickness and emission intensity was observed with increase in number of bilayers deposited in all multilayer films.


1997 ◽  
Vol 488 ◽  
Author(s):  
DeQuan Li ◽  
M. Lütt ◽  
Xiaobo Shi ◽  
M. R. Fitzsimmons

AbstractThe layer-by-layer growth of film structures consisting of sequential depositions of oppositely charged polymers and macrocycles (ring-shaped molecules) have been constructed using molecular self-assembly techniques. These self-assembled thin films were characterized with X-ray reflectometry, which yielded (1) the average electron density, (2) the average thicknesses, and (3) the roughness of the growth surface of the self-assembled multilayer of macrocycles and polymers. These observations suggest that inorganic-organic interactions play an important role during the initial stages of thin-film growth, but less so as the thin film becomes thicker. Optical absorption techniques were also used to characterize the self-assembled multilayers. Phorphyrin and phthalocyanine derivatives were chosen as the building blocks of the self-assembled multilayers because of their interesting optical properties.


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