Linearly polarized emission from self-assembled microstructures of mesogenic polythiophenes

Abstract

This work reports on linearly polarized photoluminescence and electroluminescence through spontaneous self-assembly of mesogenic polythiophenes under ambient conditions. A systematic structural variation and different alkyl chain lengths lead to three series of closely related mesogenic polythiophenes viz.; TPn, TNn and TVn. Polarized light emitting diodes fabricated from TV12 by solution processing with the configuration of ITO/PEDOT:PSS/Polymer/Al show linearly polarized electroluminescence with a dichroic ratio of 14.32. Spun thin films of TV12 elicited a dichroic ratio of 15.02 in photoluminescence. Studies using a range of techniques such as; atomic force microscopy, grazing incidence X-ray diffraction, fluorescence anisotropy, linear dichroism, fluorescence lifetime and dynamic light scattering reveal that the presence of highly ordered self-assembly was responsible for the dimensional confinement of optoelectronic properties. The ordering in the thin films originates from vinyl groups in the side chains of the TV12 polymer. Further studies on device characteristics show higher charge carrier mobility in polymers with vinyl side chains. Solution processed PLEDs show a maximum brightness of 863 cd m(-2) for the TP12 polymer and TV12 based LEDs show a maximum brightness of 524 cd m(-2).

Controlled decoration of the surface with macromolecules: polymerization on a self-assembled monolayer (SAM)

“…Those types of thiophene polymers are important for molecular electronic devices. 61,62 The grafting of P3HT brushes was studied as a function of ''click'' reaction time; it was observed that the growth of the brushes was governed by a diffusion controlled process. 45 In an alternative way, the alkyne functionalized surface was used for ''click'' reaction to immobilize azide functionalized polymers.…”

Highly Polarized Fluorescent Illumination Using Liquid Crystal Phase

“…To demonstrate the versatility of our method, we extended the study to investigate manipulation of the fluorescent illumination from the aligned B7 domains. There have been many studies on the development of polarized fluorescent illumination, utilizing light-emitting inorganic multilayer structures, quantum rods, , and light-emitting polymers with liquid crystalline substitutes. − However, it often requires prepatterned templates, expensive equipment, and complex processing steps. In this study, to realize linearly polarized illumination, we require only an aligned B7 phase that has self-photoemissive characteristics.…”

“… , Thus, the aligned B7 phase can yield polarized fluorescence, which is a common requirement for electro-optic applications such as LC displays, optical bioimaging systems, and optical communications . In terms of the manipulation of polarized fluorescence illumination, fluorescent LC materials may also have major advantages compared to polymeric − or inorganic systems, , owing to their stimuli responsive self-assembling behavior under various types of external perturbations such as electric and magnetic fields.…”

Experimental and Computational Study of Thiophene Based Calamitic Liquid Crystals

“…The liquid cr ystalline proper ty and mesophase transition enthalpies of structurally comparable molecules were investigated by polarizing optical microscope (OPM), About 2 mg of the sample was taken between glass cover slips. Only (2TWC10) exhibits typical nematic droplets further cooling gives threads texture with two or four brushes [35][36][37] . Typically, this observation is common in three rings or four rings calamitic mesogens.…”

“…In addition, the direct linking of thiophene and phenyl ring in the molecule lead to insufficient aspect ratio of the molecule which is essential for mesophase property. So, decrease in lateral dipolar interactions due to terminal alkyl chain and insufficient aspect ratio of molecule due to direct linking of thiophene and phenyl ring in the molecule lead to absence of mesophase in S12 molecule 37 .…”