Investigation of poly(arylenevinylene)s, 40. Electrochemical studies on poly(<i>p</i>‐phenylenevinylene)s

Helbig, Manfred; Hörhold, Hans‐Heinrich

doi:10.1002/macp.1993.021940608

Cited by 59 publications

(34 citation statements)

References 22 publications

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“…If the energy of the mobile P þ and the doubly occupied bipolaron state is similar, isoenergetic hopping can occur. The final energy of the bipolaron state will be reduced by the correlation energy, which has been reported to be $0:2eV [26], and may thus be compatible with the trapping energy. The bipolaron formation process in accordance with our EDMR results is shown in Fig.…”

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confidence: 71%

Bipolaron Formation in Organic Solar Cells Observed by Pulsed Electrically Detected Magnetic Resonance

et al. 2010

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We report the observation of a spin-dependent dark transport current, exhibiting spin coherence at room temperature, in a -conjugated polymer-fullerene blend using pulsed electrically detected magnetic resonance. The resonance at g ¼ 2:0028ð3Þ is due to polarons in the polymer, and exhibits spin locking at high microwave fields. The presence of an excess of fullerene, and the operating voltage (1 V) used, suppresses negative polaron formation in the polymer. It is concluded that spin-dependent transport is due to the formation of positive bipolarons. DOI: 10.1103/PhysRevLett.105.176601 PACS numbers: 72.80. Le, 71.38.Mx, 72.25.Rb, 76.30.Mi Organic semiconductors provide a range of commercial optoelectronic display devices, and show great promise in the field of photovoltaics (PV) [1][2][3][4] if improved efficiency, combined with low cost and ease of production, can be achieved. In addition, the weak spin-orbit coupling of organic semiconductors is attractive for carrier spin transport and manipulation, and is driving efforts to develop spintronic devices [5]. All these applications depend upon detailed knowledge of the relevant transport processes, in particular, those influenced by spin selection rules. The observation of large magnetoresistance (MR) has, for example, attracted a range of explanations [6][7][8][9], but aspects of the proposed mechanisms remain controversial [10].Conduction in disordered organic semiconductors is dominated by hopping of charge carriers between localized states. Because of strong electron-phonon coupling the carriers are polarons. Oppositely charged polarons can form excitons and eventually recombine; the process normally depends on the spin state of the coupled pair immediately prior to exciton formation. In addition, the strong coupling between carriers and the environment can markedly reduce the energy cost of doubly occupying states. Two like-charge polarons can form a bipolaron, the correlation energy between the pair and the lattice deformation lowering the formation energy [11]. However, the on-site exchange requires that the final state is a spin singlet, and bipolaron formation will be ''spin-blocked'' if two polarons have the same spin component along the common axis of quantization [8].Organic PV devices have advanced dramatically with the development of bulk heterojunction materials [2][3][4], which comprise a -conjugated polymer blended with an electron acceptor such as a fullerene derivative. The two phase-separated components give interpenetrating networks with vastly increased interfacial regions [3]. The PVeffect is due to photoexcitation of the polymer, followed by highly efficient electron transfer to the fullerene phase. Positive polarons (P þ ) are transported through the polymer matrix, negative polarons through the fullerene phase, efficiently suppressing carrier loss by P þ P À recombination. However, unipolar transport to the electrodes may be influenced by bipolaron formation. Gaining insight into this process, which affects charge carrier collection...

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confidence: 71%

Bipolaron Formation in Organic Solar Cells Observed by Pulsed Electrically Detected Magnetic Resonance

et al. 2010

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“…A further limitation to both of these polymerization routes is the fact that strictly alternating copolymers such as M3EH-PPV or meta-phenylene polymers cannot be prepared in this way. Macromol 25) Further methods for the synthesis of dialkoxy-substituted PPVs include polycondensation by aryl/ethylene cross-coupling via Heck or Suzuki reactions 14,15) . Both of these routes yield high molecular weight materials but need relatively expensive monomers.…”

Section: Introductionmentioning

confidence: 99%

Investigation of poly(arylene vinylene)s, 41. Synthesis of soluble dialkoxy-substituted poly(phenylene alkenylidene)s by applying the Horner-reaction for condensation polymerization

Pfeiffer

Hörhold²

1999

Macromol. Chem. Phys.

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SUMMARY: Soluble poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene-1,2-ethenylene] (MEH-PPV) and its alternating copolymer poly[2,5-dimethoxy-1,4-phenylene-1,2-ethenylene-2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene-1,2-ethenylene] (M3EH-PPV) were successfully synthesized by condensation polymerization of substituted terephthalaldehydes with substituted xylylene bisphosphonates via the Horner reaction. This polycondensation method was also applied to the synthesis of the analogous poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene-1,3-butadiene-1,4-diyl] (MEH-PPB), which contains a 1,3-butadiene instead of a vinylene unit. The optical data of MEH-PPV and M3EH-PPV (solid film, abs. ) and possess all-trans structure. Optical quality solid films are easily prepared from these polymers by solution processing. Blends with phenyl-substituted PPV derivatives can also be prepared in this way. This combination of properties is highly desirable for many light-emitting, nonlinear optical, and photoelectrical applications.

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“…Nevertheless, the majority of OPVs has a regular structure with one of the repeat units shown in Table 11 [53,[101][102][103][104], phenyl [105,106], phanes [107,108], ferrocene [109,110], porphyrene [111], fullerene [71,112], SO 3 H [108, [113][114][115].…”

Section: Synthesismentioning

confidence: 99%

Defined‐length Carbon‐rich Conjugated Oligomers

Meier

2006

Carbon‐Rich Compounds

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Investigation of poly(arylenevinylene)s, 40. Electrochemical studies on poly(p‐phenylenevinylene)s

Cited by 59 publications

References 22 publications

Bipolaron Formation in Organic Solar Cells Observed by Pulsed Electrically Detected Magnetic Resonance

Bipolaron Formation in Organic Solar Cells Observed by Pulsed Electrically Detected Magnetic Resonance

Investigation of poly(arylene vinylene)s, 41. Synthesis of soluble dialkoxy-substituted poly(phenylene alkenylidene)s by applying the Horner-reaction for condensation polymerization

Defined‐length Carbon‐rich Conjugated Oligomers

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