The morphological dependence of charge transport in a soluble luminescent conjugated polymer

Tan, Czek Haan; Inigo, Anto R.; Fann, Wunshain; Wei, Pei‐Kuen; Perng, Gung-Yeong; Chen, Shaw-An

doi:10.1016/s1566-1199(02)00037-x

Cited by 42 publications

(26 citation statements)

References 29 publications

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“…Fann's group reported that, for MEH-PPV, aggregates form after thermal annealing and give a significant influence on charge transport as revealed by Time-of-Flight (TOF) measurements. 29 The film cast from its solution in toluene features non-dispersive hole transport and the hole mobility under an electric field of 1.2´10 5 V/cm is found to be 9.8´10 -6 cm 2 /V·s. After thermal annealing, its charge transport becomes dispersive and the hole mobility drops by about one orders of magnitude to 4.5´10 -7 cm 2 /V·s at the same electric field.…”

Section: -3 the Effect Of Aggregates On Charge Transport And Devicementioning

confidence: 95%

A Review on the Emitting Species in Conjugated Polymers for Photo‐ and Electro‐luminescence

Chen¹,

Jen²,

Lu³

2010

J Chinese Chemical Soc

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In conjugated polymers, fluorescence from a single polymer chain, which is contrasted with measurements on an ensemble or bulk collection of molecules, can provide important information about conformation of single polymer chain and energy transfer between different conjugation length segments within single polymer chain. On the other hand, the presence of intrachain or interchain interactions plays an important role on their photoluminescence (PL) and electroluminescence (EL) properties. In addition to non-interacting isolated chain, there are five interacting emitting species, namely: photo-excited dimers including excimer and exciplex, electrical-excited dimers including electromer and electroplex, and aggregate. Excimer, exciplex, and aggregate can lead to a generation of new peak with featureless structure on the longer wavelength side in the fluorescence spectrum and usually cause a lowering in PL quantum efficiency. These three emitting species can be observed in both PL and EL spectra. In addition, electromer and electroplex only appear in EL spectrum but not in PL spectrum. The presence of electromer and electroplex also leads to a new peak at longer wavelength side. Another non-interacting ground-state emitting species, b phase, consists of a chain segment with a more coplanar conformation and therefore results in a longer conjugation and clear vibronic transitions.

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Section: -3 the Effect Of Aggregates On Charge Transport And Devicementioning

confidence: 95%

A Review on the Emitting Species in Conjugated Polymers for Photo‐ and Electro‐luminescence

Chen¹,

Jen²,

Lu³

2010

J Chinese Chemical Soc

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“…Variations in the mobility of over an order of magnitude have been observed in PPVs as a result of different solvents, [39] different deposition conditions, or annealing. [40] An increase of more than two orders of magnitude has recently been demonstrated in our laboratory for a precursor route dimethoxy-PPV polymer upon annealing. [41] In all cases, these changes were attributed to chain packing.…”

Section: Mechanism For Hole-mobility Enhancementmentioning

confidence: 99%

“…A conceivable explanation is that the ªtrapsº causing energetic disorder are due to the packing of adjacent polymer chains into lower-energy crystallites, [40,52] which are not formed when PCBM is present. Indeed, it has previously been suggested that the disorder in PPVs is more structural than energetic in origin.…”

Section: Mechanism For Hole-mobility Enhancementmentioning

confidence: 99%

Ambipolar Charge Transport in Films of Methanofullerene and Poly(phenylenevinylene)/Methanofullerene Blends

et al. 2005

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Herein, we report experimental studies of electron and hole transport in thin films of [6,6]‐phenyl C61 butyric acid methyl ester (PCBM) and in blends of poly[2‐methoxy‐5‐(3′,7′‐dimethyloctyloxy)‐1,4‐phenylenevinylene] (MDMO‐PPV) with PCBM. The low‐field hole mobility in pristine MDMO‐PPV is of the order of 10–7 cm2 V–1 s–1, in agreement with previous studies, whereas the electron mobility in pristine PCBM was found by current‐density–voltage (J–V) measurements to be of the order of 10–2 cm2 V–1 s–1, which is about one order of magnitude greater than previously reported. Adding PCBM to the blend increases both electron and hole mobilities, compared to the pristine polymer, and results in less dispersive hole transport. The hole mobility in a blend containing 67 wt.‐% PCBM is at least two orders of magnitude greater than in the pristine polymer. This result is independent of measurement technique and film thickness, indicating a true bulk property of the material. We therefore propose that PCBM may assist hole transport in the blend, either by participating in hole transport or by changing the polymer‐chain packing to enhance hole mobility. Time‐of‐flight mobility measurements of PCBM dispersed in a polystyrene matrix yield electron and hole mobilities of similar magnitude and relatively non‐dispersive transport. To the best of our knowledge, this is the first report of hole transport in a methanofullerene. We discuss the conditions under which hole transport in the fullerene phase of a polymer/fullerene blend may be expected. The relevance to photovoltaic device function is also discussed.

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“…This is in agreement with recent work by several other groups. 13,28,[59][60][61][62] These findings have implications for the design and application of polymers in electro-optic devices 1 : these devices work by converting light to excitons and/or charges and vice versa. Hence, by controlling interchain distances, properties that are important to the operation of such devices can be modified.…”

Section: Figmentioning

confidence: 99%

Interchain effects in the ultrafast photophysics of a semiconducting polymer:THztime-domain spectroscopy of thin films and isolated chains in solution

et al. 2005

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We compare the generation and decay dynamics of charges and excitons in a model polymer semiconductor ͑MEH-PPV͒ in solution and drop-cast thin films, by recording the sub-ps transient complex conductivity using THz time-domain spectroscopy. The results show that the quantum efficiency of charge generation is two orders of magnitude smaller in solution ͑ϳ10−5 ͒ than in the solid film ͑ϳ10 −3 ͒. The proximity of neighboring chains in the films apparently facilitates ͑hot͒ exciton dissociation, presumably by allowing the electron and hole to separate on different polymer strands. For both samples, photoexcitation leads to the predominant formation of bound charge pairs ͑excitons͒ that can be detected through their polarizability. Surprisingly, the polarizability per absorbed photon is a factor of 3 larger in solution than in the film, suggesting that interchain interactions in the film do not result in a substantial delocalization of the exciton wave function.

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The morphological dependence of charge transport in a soluble luminescent conjugated polymer

Cited by 42 publications

References 29 publications

A Review on the Emitting Species in Conjugated Polymers for Photo‐ and Electro‐luminescence

A Review on the Emitting Species in Conjugated Polymers for Photo‐ and Electro‐luminescence

Ambipolar Charge Transport in Films of Methanofullerene and Poly(phenylenevinylene)/Methanofullerene Blends

Interchain effects in the ultrafast photophysics of a semiconducting polymer:THztime-domain spectroscopy of thin films and isolated chains in solution

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