A Tetrahedral Oligo(phenylenevinylene) Molecule of Intermediate Dimensions: Effect of Molecular Shape on the Morphology and Electroluminescence of Organic Glasses

Abstract

Tetrakis[(4‐(4′‐(2″,5″‐dioctyloxy‐4″‐(4‴‐(2′‴,5′‴‐dioctyloxy‐4′‴‐styryl)styryl)styryl)styryl)styryl)phenyl]methane (T‐6R‐OC8H17) is an organic chromophore that consists of four optoelectronic fragments (“arms”) connected to a tetrahedral point of convergence (carbon). Bulk samples are amorphous as determined by powder diffraction, while differential scanning calorimetry (DSC) is sometimes ambiguous. Film forming properties were studied by atomic force microscopy (AFM) and fluorescence microscopy as a function of casting solvent and heat treatment. The film forming qualities are useful for the fabrication of light‐emitting diodes with low turn‐on voltages. Device performance is also history dependent. The relationship between bulk morphology, film topology, photoluminescence (PL) properties, and light‐emitting diode (LED) performance is discussed. A comparison of these compounds against the parent oligo(phenylenevinylene) arms, with respect to morphology, topology, and PL properties is also presented.

[2+2] Photodimerization and photopolymerization of diphenylhexatriene crystals utilizing perfluorophenyl–phenyl stacking interactions

“…The efficient photoreaction due to the transparency of the products was similarly observed for the crystalline-state Z-E photoisomerization of (Z,E,Z)-1,6-diphenyl-1,3,5-hexatrienes [30]. Considering that molecules with nonplanar and bulky structures tend to be amorphous in the solid state [31,32], the formation of the amorphous states of products in the present case should mainly be attributed to the molecular shape of 4 itself (and probably those of the trimer and higher oligomers themselves).…”

Solid-State [2+2] Photodimerization and Photopolymerization of α,ω-Diarylpolyene Monomers: Effective Utilization of Noncovalent Intermolecular Interactions in Crystals

“…For amorphous molecular materials, very disordered structures are usually required [ 153 , 154 ]. [2+2] Photocycloaddition of olefins will easily give highly disordered and bulky structures.…”

“…[2+2] Photocycloaddition of olefins will easily give highly disordered and bulky structures. As in a molecule having a tetrahedral carbon framework [ 153 ], various functional groups can be attached as four arms to the cyclobutane ring carbons, leading to the formation of 'functional amorphous materials' ( Figure 11 ).…”

Organic Light Emitting Diodes Based on Functionalized Oligothiophenes for Display and Lighting Applications

“…Since theoretical calculations, optical and CV data indicate that V-shaped oligothiophene-S,S-dioxides have electronic and optical features very similar to those of the corresponding linear compounds, the reason for the improved performances was ascribed to the much better film-forming properties of V-shaped compared to linear compounds and to changes in morphology from crystalline to amorphous films. There are several studies in the literature indicating that amorphous thin films, obtained either by vapor deposition or spin coating, enhance the electroluminesce properties (Robinson et al, 2001;Su et al, 2002;Doi et al, 2003). The good film-forming properties and the amorphous morphology of V-shaped oligomers are due to their branched structure and asymmetric molecular conformation.…”