Conjugated polymers luminescent

A number of studies have suggested that because the electron transport mobility is lower than that of holes and because there is a higher density of electron traps, true balance has not yet been attained i.e. the device performance is limited by the electron transport [163]. In an attempt to address this problem, the effect of blending electron transport materials into the conjugated luminescent polymer was studied. The best results were obtained with (2-(4-biphenyl)-5-(4-tert-butylphenyl)l,3,4-oxidiazole, Bu-PBD, which was... 

Unlike the covalent functionalization approach, noncovalent functionalization provides an alternative method to modify and tailor the surface properties of CNTs in order to increase their solubility in solvents or compatibility with polymer matrix. In this method, the tubular surface of a CNT is noncovalently wrapped with polymer chains due to van der Waals attractive forces or through tt-tt interactions. This noncovalent wrapping approach has also been widely used and is particularly attractive because it offers the possibility of attaching chemical handles without affecting the electronic network of the nanotubes [42-45]. Coleman et al [46-49] illustrated an example of noncovalent wrapping by tt-tt interaction between CNTs and poly(m-phenylenevinylene-co-2,5-dioctoxy-p-phenylene vinylene) (PmPV), a conjugated luminescent polymer, to obtain a CNT-PmPV composite. 

Polymer laser diodes have been an attractive topic after the discovery of EL in conjugated polymers. Optical lasing in semiconducting luminescent polymer solutions was first... 

Phenylene-based polymers are one of the most important classes of conjugated polymers, and have been the subject of extensive research, in particular as the active materials in light-emitting diodes (LEDs) [1,2] and polymer lasers [3]. These materials have been of particular interest as potential blue emitters in such devices [4], The discovery of stable blue-light emitting materials is a major goal of research into luminescent polymers [5]. Poly(para-phenylene) (PPP, Scheme 1, 1) is a blue emitter [6], but it is insoluble and so films of PPP have to be prepared via precursor routes [7]. Substitution with long alkyl... 

Stoddart and coworkers synthesized a conjugated form of the luminescent polymer poly(metaphenylenevinylene) (PmPV, Figure 12b,i) to disperse SWNTs in chloroform (CHCb). Moreover, other functionalized PmPVs (Figure 12b,i) disperse CNTs in other solvents and provide routes to supramolecular assemblies (Figure 12b,ii). ... 

The active layer consists of a polymer having electronic conductive, ionic conductive, and luminescent properties, is blended with an ionic salt [48]. The polymer with the required properties can be realized by a blend of a conjugated and an ionic conductive polymer [481 or by specially designed polymers [71-73],... 

Table 13-1. Chemical structures of representative luminescent conjugated polymers.

For copolymers of structure I, for both types of side-chains, there is a striking similarity with the optical properties of the corresponding models the absorption and photoluminescence maxima of the polymers arc only 0.08-0.09 eV red-shifted relative to those of the models, as shown in Figure 16-9 (left) for the octyloxy-substituted compounds. The small shift can be readily explained by the fact that in the copolymers the chromophorcs are actually substituted by silylene units, which have a weakly electron-donating character. The shifts between absorption and luminescence maxima are exactly the same for polymers and models and the width of the emission bands is almost identical. The quantum yields are only slightly reduced in the polymers. These results confirm that the active chro-mophores are the PPV-type blocks and that the silylene unit is an efficient re-conjugation interrupter. 

A comparison of the absorption and emission spectra of Ooct-OPV5 with those of the fully conjugated, similarly substituted polymer Ooct-PPV shows that the absorption and luminescence maxima of the five-ring model compound are only slightly blue-shifted relative to those of the polymer (see Fig. 16-11). Hence, the... 

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