Electrostatic Self-Assembly of Multilayer Noncentrosymmetric Thin Films and Devices

1999 ◽  
Vol 561 ◽  
Author(s):  
K. M. Lenahan ◽  
T. Zenga ◽  
Y. Liu ◽  
Y.-X. Wang ◽  
W. Zhao ◽  
...  
Keyword(s):  
Thin Films ◽  
Self Assembly ◽  
Dipole Moments ◽  
Low Cost ◽  
Optical Loss ◽  
Deposition Process ◽  
Multilayer Thin Films ◽  
Nonlinear Optical Susceptibility ◽  
Optical Susceptibility ◽  
Polyelectrolyte Solutions

ABSTRACTThe electrostatic self-assembly of multilayer thin films by alternate adsorption from polyelectrolyte solutions spontaneously leads to the formation of noncentrosymmetric structures if the molecules themselves have net dipole moments. Significant second-order nonlinear optical susceptibility has been observed in such films, using both commercially available chromophores and molecules specifically designed to yield an enhanced net dipole moment. Recent results indicate the capability to fabricate piezoelectric films using the same method. The nature of the deposition process results in an alignment of the chromophores that is stable over time and to temperatures up to 150°C, in contrast with poled polymers. ESA films offer the additional major advantages of excellent homogeneity and low optical loss, high thermal and chemical stability, and low cost.

Directed Self-Assembly of Multilayer Thin Films of ZnS and Gold Nanoparticles by Modified Polyelectrolyte Deposition Technique

2005 ◽  
Vol 901 ◽  
Author(s):  
S. H. M. Jafri ◽  
A. B. Sharma ◽  
Chanchana Thanachayanont ◽  
Joydeep Dutta
Keyword(s):  
Thin Films ◽  
Gold Nanoparticles ◽  
Steric Hindrance ◽  
Self Assembly ◽  
Building Blocks ◽  
Deposition Process ◽  
Zinc Sulphide ◽  
Double Layers ◽  
Multilayer Thin Films ◽  
Layer By Layer

AbstractFabrication strategies based on mechanisms of self-assembly are now widely being recognized as inevitable tools in nanotechnology. Self-organized construction of advanced materials and devices may be done starting with tailor made nanoparticles as building blocks. Multilayer thin films of gold, zinc sulphide and manganese doped zinc Sulfide nanoparticles were fabricated by a modified polyelectrolyte deposition process. A prerequisite to utilization of colloids for the fabrication of uniform layers is that they remain in suspension and resist unwanted agglomeration. The stability of colloids is generally achieved either by electrostatic stabilization, involving the creation of an electrical double layers arising from ions intentionally adsorbed on the surface of the particle and associated counter ions that surround the particle, or by steric hindrance that is achieved by the adsorption of macromolecules on the surface of the particles. The inherent necessity to introduce electrostatic or steric hindrance to avoid colloidal agglomeration was utilized to induce self-assembly of multilayers applying similar concept used for the layering of polyelectrolytes. Polyacrylic acid was used as the polyanion and chitosan as the polycation for the deposition process. Upto 100 layers of nanoparticles were constructed and films that were found to be stable and uniform over the substrate. The layer-by-layer deposition of multilayers of several different structures was prepared and devices showing resistive and capacitive electrical characteristics have been fabricated. The onset of electrical conduction in the resistive devices could be varied by introducing a dielectric interlayer between gold nanoparticles and by introducing a gold overlayer on the zinc sulphide nanoparticle devices.

Large Third-Order Nonlinear Optical Susceptibility of Rh-Doped BaTiO 3 Thin Films Prepared by Pulsed Laser Deposition

2001 ◽  
Vol 18 (12) ◽  
pp. 1598-1600 ◽  
Author(s):  
Yang Guang ◽  
Wang Huan-Hua ◽  
Tan Guo-Tai ◽  
Jiang An-Quan ◽  
Zhou Yue-Liang ◽  
...  
Keyword(s):  
Thin Films ◽  
Pulsed Laser Deposition ◽  
Nonlinear Optical ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Third Order ◽  
Nonlinear Optical Susceptibility ◽  
Optical Susceptibility

Investigations of New Self-Assembled Multilayer Thin Films Based on Alternately Adsorbed Layers of Polyelectrolytes and Functional Dye Molecules

1995 ◽  
Vol 413 ◽  
Author(s):  
Dongsik Yoo ◽  
Jin-kyu Lee ◽  
M. F. Rubner
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Self Assembly ◽  
Fluorescent Dyes ◽  
Multilayer Thin Films ◽  
Layer By Layer ◽  
Dye Molecules ◽  
Ph Indicator ◽  
Light Emitting ◽  
Thin Film Devices

ABSTRACTThe layer-by-layer self-assembly of a number of different functional dye molecules has been accomplished via the alternate spontaneous adsorption of polyelectrolytes and ionic dyes from dilute solutions. Multilayer thin films containing such functional dyes as pH indicator dyes, infrared absorbing dyes, porphyrin dyes and various fluorescent dyes have been successfully fabricated and their electrical and opt, 2al properties examined. Multilayers containing a newly synthesized ionic ruthenium based polypryidyl dye have been utilized to fabricate light emitting thin film devices with high brightness (ca. 100 cd/m2) at voltages in the range of 5–10 volts. These new light emitting thin film devices exhibit excellent stability when compared to devices based on conjugated polymers such PPV. The fabrication and device evaluation of new heterostructure thin films based on this new light emitting dye as well as the properties of other multilayer thin films containing dye molecules are presented.

Layer-by-Layer Thin Films of Alginate/Chitosan and Hyaluronic Acid/Chitosan with Tunable Thickness and Surface Roughness

2014 ◽  
Vol 783-786 ◽  
pp. 1226-1231 ◽  
Author(s):  
Thiago Bezerra Taketa ◽  
Marisa Masumi Beppu
Keyword(s):  
Thin Films ◽  
Hyaluronic Acid ◽  
Self Assembly ◽  
Polymer Chains ◽  
Layer By Layer ◽  
Natural Polymers ◽  
Force Microscopy ◽  
Atomic Force ◽  
Polyelectrolyte Solutions ◽  
Oppositely Charged

Layer-by-layer (LbL) is a bottom-up technique used for construction of films with self-assembly and self-organizing properties. In most cases, the fundamental driving force for the formation of these films is originated from the electrostatic interaction between oppositely charged species. The charged segments of polyelectrolytes behave as small building units and their orientation and position can be designed to target structures of great complexity. Furthermore, the technique enables the use of various materials, including natural polymers. In this work, we chose the cationic biopolymer chitosan (CHI) and the negative polyelectrolytes sodium alginate (ALG) and hyaluronic acid (HA). The aim of this study was to evaluate the effect of ionic strength (0 versus 200 mM) and pH (3 versus 5) on ALG/CHI and HA/CHI nanostructured multilayered thin films properties. From profilometry and atomic force microscopy (AFM) analyses, changes in thickness and roughness of the coatings were monitored. The presence of salt in polyelectrolyte solutions induced the polymer chains to adopt conformations with more loops and tails and this arrangement in solution was transmitted to films, resulting in rougher surfaces. Furthermore, the film thickness can be precisely controlled by adjusting the pH of the polyelectrolyte solution. The variation of these parameters shows that it is possible to molecularly control chemical and structural properties of nanostructured coatings, thus opening up new possibilities of application (e.g. cell adhesion).

scholarly journals Preparation and Characterization of Self-Assembled Manganese Dioxide Thin Films

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Suh Cem Pang ◽  
Suk Fun Chin ◽  
Chian Ye Ling
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Manganese Dioxide ◽  
Self Assembly ◽  
Electrode Materials ◽  
Thin Film Deposition ◽  
Deposition Process ◽  
Film Deposition ◽  
Deposition Duration ◽  
Self Assembled

Thin films of manganese dioxide (MnO2) were prepared by self-assembly of MnO2nanoparticles directly unto nickel-coated poly(ethylene terephthalate) flexible films using the newly developed horizontal submersion process. The thickness of deposited thin films was controllable by the deposition duration. This horizontal submersion deposition process for thin-film deposition is relatively easy, simple, and cost effective. Effects of deposition duration and calcination temperatures on the microstructure and electrochemical properties of self-assembled MnO2thin films were investigated. Optimized MnO2thin films exhibited high charge capacity, good cycling reversibility, and stability in a mild aqueous electrolyte and are thus promising electrode materials for the fabrication of thin-film electrochemical capacitors.

NEW TECHNIQUE TO DEPOSIT THIN FILMS OF CARBON NANOTUBES BASED ON ELECTROSTATIC CHARGE DEPOSITION AND THEIR APPLICATION FOR ALCOHOL DETECTION

2009 ◽  
Vol 08 (04n05) ◽  
pp. 443-453 ◽  
Author(s):  
VASUDA BHATIA ◽  
VIKESH GAUR ◽  
VINOD K. JAIN
Keyword(s):  
Thin Films ◽  
Carbon Nanotubes ◽  
Self Assembly ◽  
Electrostatic Force ◽  
Low Cost ◽  
New Technique ◽  
Enhanced Sensitivity ◽  
Time Operation ◽  
Specialized Equipment ◽  
Multi Walled Carbon Nanotubes

A new technique based on an electrostatic-force-directed-self-assembly was developed to fabricate thin films of multi-walled carbon nanotubes (MWCNTs) on thin dielectric wires. This technique was further developed to achieve functionalization of the nanotubes via acid-free dry route in a few seconds. The functionalization was confirmed by Fourier transform infrared and Raman spectroscopic measurements. The electrostatically self-assembled films provided significantly enhanced sensitivity for detection of alcohol vapors. Sensors were tested for response of alcohol concentrations as low as 200 ppm (parts per million) with a sensitivity of 4% and high repeatability. Recovery of sensors was observed to be within 200 s. Selectivity of the sensors for different organic vapors was defined based on the recovery time. Operation of sensors did not require high temperatures. It was realized that corona-based electrostatic self-assembly (CESA) pattering technique for batch fabrication of the sensors was fast, simple, low-cost, and required no specialized equipment.

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