Spectroscopic and Morphological Properties of Divinylbenzoxazolylbiphenyl Thin Films

Abstract

The thin organic films based on 4,4'-bis-[(Z)-1-(1,3-benzoxazol-2-yl-2-ethenyl)]biphenyl and its partly fluorinated derivatives are studied. Absorption, luminescence, and excitation spectra, luminescence decay and film morphology were found to depend sensitively on the changes in molecule structure, nature and temperature of the substrate, as well as the thermovacuum deposition rate, being the origins of bad reproducibility of the optical properties of such films. Molecular aggregation with chromophore dipoles arranged parallel to each other has been observed in absorption and luminescence spectra. The fluorescence characteristics can be explained by the combination of radiation of aggregated and non-aggregated molecules. The main characteristics of the molecules under study are calculated using DFT approach. The unusual behaviour of photodegradation in fluorinated film is found.

Optical properties of composite structure based on ZnO microneedles and Alq3 thin film

“…α-and β-phases have two mer-Alq 3 molecules in a unit cell, while δ-phase has four fac-Alq 3 per unit cell [23]. Also, the morphology of vacuum deposited organic lms depends strongly on the substrate [32]. Zinc oxide nanostructure was employed as catalyst in organic syntheses and transformations [33].…”

Electric Field Oriented Nanostructured Organic Thin Films with Polarized Luminescence

“…The observed difference in electric field behavior of these molecules can be explained by the difference in the dipole moment. More specific techniques like positron annihilation spectroscopy may be needed to analyze the details [ 21 , 22 ], but it can be noticed that the morphology of vacuum deposited organic films depends strongly on the type of substrate and its temperature [ 23 ].

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Influence of π–π Hyperconjugation Effect on Thermal, Morphological, and Photoelectronic Properties of Non-Conjugated Pyrene Derivatives

“…In varying solvent or temperature, different aggregation morphologies could be prepared, resulting in wide differences in luminescent properties. 16,17 As to the molecular structure modifying, the introduction of long-chained alkoxy could increase the solubility and rheological properties of conjugated molecule, and then improve the film-forming capability, leading to optimized spin-coated film morphology. 18 Usually, as for one material, a more aggravated aggregation state led to red-shifted and broader absorption spectra.…”

“…In the solid or aggregation state, the conjugated aromatic hydrocarbon tends to form excimer and/or exciplex due to the intermolecular interaction including π–π stacking, electrostatic attractions and van der Waals force, which, in most time, results in a drastic decrease of their luminescence efficiency. , Studies on the aggregation state of organic luminescence materials revealed that the aggregation morphology was dominated by molecular structure of the materials, , temperature, solvent, and other kinetic parameters. In varying solvent or temperature, different aggregation morphologies could be prepared, resulting in wide differences in luminescent properties. , As to the molecular structure modifying, the introduction of long-chained alkoxy could increase the solubility and rheological properties of conjugated molecule, and then improve the film-forming capability, leading to optimized spin-coated film morphology . Usually, as for one material, a more aggravated aggregation state led to red-shifted and broader absorption spectra …”