Poly para-phenylene vinylene

Concerning the nature of electronic traps for this class of ladder polymers, we would like to recall the experimental facts. On comparing the results of LPPP to those of poly(para-phenylene vinylene) (PPV) [38] it must be noted that the appearance of the maximum current at 167 K, for heating rates between 0.06 K/s and 0.25 K/s, can be attributed to monomolecular kinetics with non-retrapping traps [26]. In PPV the density of trap states is evaluated on the basis of a multiple trapping model [38], leading to a trap density which is comparable to the density of monomer units and very low mobilities of 10-8 cm2 V-1 s l. These values for PPV have to be compared to trap densities of 0.0002 and 0.00003 traps per monomer unit in the LPPP. As a consequence of the low trap densities, high mobility values of 0.1 cm2 V-1 s-1 for the LPPPs are obtained [39]. 

Several attempts to use otganic polymeric semiconductors as the active component in photovoltaic devices have been reported during the last two decades. Interest in the photovoltaic properties of conjugated polymers like polyacelylcne, various derivatives of polythiophenes and poly(para-phenylene vinylene)s arose from... 

Light-emitting polymers [46,48] are a more recent development and may eventually prove superior to small-molecule OLED. Typical polymers are the green poly(para-phenylene vinylene) (PPV 53), the orange-red dialkoxy derivatives (54), and the blue polyfluorene (55) [48],... 

O. Lhost and J. L. Bredas, ]. Phys. Chem., 96, 5279 (1992). Theoretical Study of Torsion Potentials in traws-Stilbene and Substituted truns-Stilbenes Modeling Torsions in Poly(para-phenylene vinylene) and Derivatives. 

FIGURE 1.2. Molecular structure of widely used it-conjugated and other polymers (a) poly(para-phenylene vinylene) (PPV) (b) a (solid line along backbone) and it ( clouds above and below the a line) electron probability densities in PPV (c) poly(2-methoxy-5-(2 -ethyl)-hexoxy-l,4-phenylene vinylene) (MEH-PPV) (d) polyaniline (PANI) (d.l) leucoemeraldine base (LEB), (d.2) emeraldine base (EB), (d.3) pernigraniline base (PNB) (e) poly(3,4-ethylene dioxy-2,4-thiophene)-polystyrene sulfonate (PEDOT-PSS) (f) poly(IV-vinyl carbazole) (PVK) (g) poly(methyl methacrylate) (PMMA) (h) methyl-bridged ladder-type poly(jf-phenylene) (m-LPPP) (i) poly(3-alkyl thiophenes) (P3ATs) (j) polyfluorenes (PFOs) (k) diphenyl-substituted frares -polyacetylenes (f-(CH)x) or poly (diphenyl acetylene) (PDPA). 

Processing through a precursor route involves the use of an intermediate, processible polymer that can be later converted into the fully conjugated material. It is most often used with poly(para-phenylene vinylene (PPV), a relatively stable and insoluble polymer that can be manipulated as soluble precursor polymers to form films and fibers. There are many different... 

Poly(arylene vinyene)s (PAVs) represent the most widely studied group of electroluminescent polymers. The parent compound poly(para-phenylene vinylene) (PPV, 1, Fig. 6.1) [5] is insoluble and so must be processed as a precursor polymer but derivatives such as MEH-PPV (2) [6] with solubilizing alkyl, aryl, silyl, or al-koxy chains show good solubility in organic solvents and so can be readily processed by techniques such as spin casting. By appropriate choice of substituents... 

FIGURE 8.9 Linear unsubstituted conjugated polymers poly(p-phenylene), poly(para-phenylene vinylene), polythiophenes, and polyfluorenes. 

Poly(para-phenylene vinylene)s from green to red light-emitting materials... 

Synthesis Poly(para-phenylene vinylene) (PPV, XI) is the archetypical fluorescent polymer. It emits a bright green-yellow light with two emission peaks at 520 nm (2.38 eV) and 550 nm (2.25 eV). Direct synthesis of XI yields an intractable,... 

FIGURE 2.2.4 Molecular and energy schemes of poly-para-phenylene-vinylene (PPV). 

Well-defined rod-coil diblock or triblock copolymers can be obtained from conjugated macro-initiators by CRP. In each case the synthetic route requires the mono- (for diblock) or di-functioimalization (triblock) of a previous conjugated polymer. For this purpose, this last one needs to be properly end capped with a high conversion and further transformed into a macro-initiator. Many examples can be found in the literature, such as poly(para phenylene vinylene)... 

Soluble polymers can likewise be prepared in the form of thin films by spinning the solution onto a substrate and then evaporating the solvent. Insoluble polymers can in suitable cases be spun in the form of their soluble precursors and then after evaporation of the solvent be converted into the insoluble polymer by elimination of the substituents which rendered them soluble. A well-known example of this is poly(para-phenylene-vinylene) (P PV). 

Figure 8.56 shows the hole current-voltage characteristic of a PPV polymer film (PPV = poly-(para-phenylene-vinylene), see Fig. 8.55) for three different film thicknesses at room temperature as a log-log plot. The hole current was attained through a suitable choice of the work functions of the electrode indium-tin oxide (ITO) injects holes, Au injects no electrons. All three characteristics are parallel. The current... 

Skaff, H., Sill, K. and Emrick,T. (2004) Quantum Dots Tailored with Poly(para-phenylene vinylene)./. Am. Chem. Soc., 126,11322-5. 

T. Offermans, S.C.J. Meskers, and R.A.J. Janssen, Charge recombination in a poly(para-phenylene vinylene)-fullerene derivative composite film studied by transient, nonresonant, hole-burning spectroscopy, J. Chem. Phys., 119, 10924—10929 (2003). 

J. D. Stenger-Smith, W. P. Norris, A. P. Chafin, and S. T. Sackinger. Process for making amino functional poly(para-phenylene vinylene)s. US Patent 5 578 699, assigned to The United States of America as represented by the Secretary of the Navy (Washington, DC), November 26,1996. 

P. Pistor, V. Chu, D. M. F. Prazeres, and J. P. Conde. pH sensitive photoconductor based on poly(para-phenylene-vinylene). Sens. Actuators, B, 123(1) 153-157, April 2007. 

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