Supramolecular Assembly Strategies Using Alternate Adsorption of Polyelectrolytes: Applications in Pled And Lc Display Devices

Abstract

We present work on the modification, processing, and analysis of ultrathin films for display devices primarily using the supramolecular assembly strategy. This involves the use of various molecular assembly techniques (organic, polymer, metal) in which layer order and functionality is achieved at defined length scales approaching that of ultrathin films (a few to several hundred nm thicknesses). The use of alternate polyelectrolyte deposition (APD) is primarily investigated in ultrathin films that have significance in the fabrication of display devices. The first application involves modifying a polymer light emitting diode (PLED) device fabricated using the ITO/MEH-PPV/Ca protocol with polyaniline derivatives. The second is the use of the “command layer” amplification concept and photo-induced alignment using polarized light with ultrathin films of azo dye/polyelectrolytes in a hybrid liquid crystal (LC) cell configuration. Both strategies rely on the use of surface sensitive spectroscopic and microscopic techniques to correlate device performance with layer ordering at the molecular level. The concept of functional ultrathin layers for device fabrication and modification is emphasized.

Ultrathin polymer coatings by complexation of polyelectrolytes at interfaces: suitable materials, structure and properties

“…8) and comprises conducting and light-emitting polymers 89,112, , other non-conjugated redox-active polymers 49,62,131,132,[200][201][202][203][204][205][206][207] , polymeric complexes such as the Cu 2+ complex of poly(ethyleneimine) 80) , Ru 2+ complex of 2,29-bipyridyl containing polymers 170-172, 200, 208) , or an Os 2+ complex of poly(vinylpyridine) 196,[209][210][211] , reactive polymers 35,87,148,[212][213][214][215][216] , polymers bearing non-linear optically active dyes 35,138,148,214,[217][218][219][220][221][222][223][224][225][226] , liquid crystalline polyelectrolytes 105,[135][136][137] , and dendrimers [227]…”

“…Not surprisingly, layer-by-layer deposition gives rise to polymer films with alternating surface properties, such as contact angle 30,187,273,363,394,398,400,436) , chemical composition 35,227,239,383,398,437) , or f-potential 32, 34-41, 46, 92, 353) . Prepared films are typically not birefringent 15,32,58,80,81,88,89,110,135,138,254,255,431) , i. e. they are isotropic in the film plane (for an exception, see ref. 93) ), and very smooth 20,29,237,270,431) .…”

“…At least for carefully chosen systems and processing parameters, film surface becomes even smoother with ongoing film growth 20,29,130) . A linear increase of the adsorbed amount, i. e. regular film growth, should imply an approximately constant roughness of the surface, still, many reports describe an increase in roughness with film growth 83,84,89,92,132,137,163,259,311,333) , thus limiting the useful thicknesses of these ESA systems. Poorly behaving systems become even turbid (cf.…”

“…The diverse suggestions comprise the use for compatibilization and protection of surfaces 68,351,362,363,366,383,384) , as well as (bio)sensors 26, 59, 69, 70, 209, 237, 238, 256, 298, 299, 315, 334-338, 341, 350, 354-358, 395) , enzyme immobilization 108, 109, 155, 267, 340, 346-349, 361, 372) , and gene transfection 342) . Other potential applications are separation membranes and chromatography columns 66,99,187,192,319,369,370,402,405,414) , conducting, lightemitting or photovoltaic devices 91, 112, 151-154, 165-167, 170-182, 185, 186, 194, 197, 200, 270-273, 277, 285, 296, 322, 328, 453) high charge density batteries 287,321,325) , modified electrodes 196,209,454) , orientation layers 88,89) , optical data storage and magnetic films 42,67,72,110,120,275,436) , or controlled particle and catalyst preparation 71,420,436) . If spherical supports are used which may be dissolved by a secondary process, hollow spheres are accessible which have been suggested for encapsulation and drug delivery 42,258,…”

Photoalignment in Ultrathin Films of a Layer-by-Layer Deposited Water-Soluble Azobenzene Dye

“…In this paper, we report the LBL fabrication and photoinduced alignment (photoalignment) of molecularly ordered ultrathin films of a small-molecule azobenzene dye (DR80) and polycations. , This molecular chromophoric dye was chosen to have sufficient charge density, photoisomerizability, and high aspect ratio for the E -isomer. The molecular assembly process was previously investigated using surface sensitive techniques such as quartz crystal microbalance (QCM), ellipsometry, UV−vis spectroscopy, X-ray reflectometry, and surface plasmon spectroscopy . Photoalignment studies showed high anisotropies after irradiation with linear polarized visible light .…”